Faculty of Economics CAMBRIDGE WORKING PAPERS IN ECONOMICS JANEWAY INSTITUTE WORKING PAPERS Climate Change and Economic Activity: Evidence from U.S. States Kamiar Mohaddes University of Cambridge Ryan N. C. Ng University of Cambridge M. Hashem Pesaran University of Southern California Mehdi Raissi IMF Washington DC Jui-Chung Yang National Taiwan University Abstract We investigate the long-term macroeconomic effects of climate change across 48 U.S. states over the period 1963-2016 using a novel econometric strategy which links deviations of temperature and precipitation (weather) from their long-term moving-average historical norms (climate) to various state-specific economic performance indicators at the aggregate and sectoral levels. We show that climate change has a long-lasting adverse impact on real output in various states and economic sectors, and on labour productivity and employment in the United States. Moreover, in contrast to most cross- country results, our within U.S. estimates tend to be asymmetrical with respect to deviations of climate variables (including precipitation) from their historical norms. Reference Details 2205 Cambridge Working Papers in Economics 2022/03 Janeway Institute Working Paper Series Published 21 January 2022 Key Words Climate change, economic growth, adaptation, United States JEL-codes C33, O40, O44, O51, Q51, Q54 Websites www.econ.cam.ac.uk/cwpe www.janeway.econ.cam.ac.uk/working-papers Climate Change and Economic Activity: Evidence from U.S. States Kamiar Mohaddesay, Ryan N. C. Ngb, M. Hashem Pesaranc, Mehdi Raissid and Jui-Chung Yange a Judge Business School and King’s College, University of Cambridge, UK b Faculty of Economics, University of Cambridge, UK c Department of Economics, University of Southern California, USA and Trinity College, University of Cambridge, UK d International Monetary Fund, Washington DC, USA e Department of Economics, National Taiwan University, Taiwan January 20, 2022 Abstract We investigate the long-term macroeconomic e¤ects of climate change across 48 U.S. states over the period 1963–2016 using a novel econometric strategy which links devia- tions of temperature and precipitation (weather) from their long-term moving-average historical norms (climate) to various state-speci…c economic performance indicators at the aggregate and sectoral levels. We show that climate change has a long-lasting adverse impact on real output in various states and economic sectors, and on labour productivity and employment in the United States. Moreover, in contrast to most cross-country results, our within U.S. estimates tend to be asymmetrical with respect to deviations of climate variables (including precipitation) from their historical norms. JEL Classi…cations: C33, O40, O44, O51, Q51, Q54. Keywords: Climate change, economic growth, adaptation, United States. We are grateful to Tiago Cavalcanti, Francis X. Diebold, Christopher Hajzler, Stephane Hallegatte, Zeina Hasna, John Hassler, Matthew E. Kahn, Per Krusell, Miguel Molico, Peter Phillips, Margit Reischer, Ron Smith, Richard Tol, Carolyn A. Wilkins and seminar participants at the International Monetary Fund (IMF), Bank of Lithuania, Bank of Canada, EPRG, Cambridge Judge Business School, the ERF 24th An- nual Conference, the 2018 MIT CEEPR Research Workshop, the 2019 Keynes Fund Research Day, National Institute of Economic and Social Research, Copenhagen Business School, Bank of England, Federal Reserve Bank of San Francisco, London School of Economics, European Central Bank, and RES 2021 Annual Con- ference for helpful comments and suggestions. We gratefully acknowledge …nancial support from the Keynes Fund. The views expressed in this paper are those of the authors and do not necessarily represent those of the IMF or its policy. yCorresponding author. Email address: km418@cam.ac.uk. 1 Introduction Kahn et al. (2021a) show that changes in the distribution of weather patterns (i.e., climate change1) are not only a¤ecting low-income countries and those in hot climates, but also advanced economies and those in cold climates (albeit to di¤erent degrees across climates and income levels).2 Using estimates from a panel of 174 countries over the past half cen- tury, they conduct a counterfactual study and show that in the absence of global mitigation policies, per-capita GDP of the United States would be 10–17 percent lower by 2100.3 Do these cross-country results hold in a within-country context (e.g., in the United States as an advanced economy with a diverse climate and partial resilience-building success against climate change)? How large are the e¤ects of climate change on state-level economic activity in the U.S.? Are there level or growth e¤ects? Are the e¤ects non-linear and/or asymmet- rical? What are the channels of impact and which sectors of the U.S. economy are a¤ected the most? What is the role of climate variability and adaptation? Answers to the these questions can inform the development of a long-term mitigation and adaptation strategy for the United States (and by extension climate policies in other advanced economies). While cross-country studies are informative, they also have drawbacks. Averaging tem- perature and precipitation data at the country level leads to a loss of information, especially in geographically diverse countries such as the United States. Using within-country data for the U.S. and a novel econometric strategy, which links deviations of temperature and precipitation (weather) from their long-term moving-average historical norms (climate) to various state-speci…c economic performance indicators at the aggregate and sectoral levels, we investigate the long-term macroeconomic e¤ects of weather patterns transformed by cli- mate change across 48 states over the period 1963–2016. The within-country geographic heterogeneity of the U.S. enables one to compare whether economic activity in ‘hot’or ‘wet’ states responds to a temperature increase in the same way as economic activity does in ‘cold’ or ‘dry’states. The richness of the United States data also allows for a more disaggregated study of the climate change–growth relationship and enables one to test whether the country at the aggregate level, parts of the country, or particular sectors of the economy have been a¤ected more by climate change. It also allows one to investigate the channels of impact: 1Weather refers to atmospheric conditions over short periods of time (e.g., temperature and precipitation). Climate refers to the long-term average and variability of weather. Climate change is a shift "in the state of the climate that can be identi…ed (e.g., via statistical tests) by changes in the mean and/or the variability of its properties, and that persists for an extended period, typically decades or longer”(IPCC (2014)). 2This …nding is in contrast with most papers in the literature— arguing that climate change has a limited impact on economic activity of advanced countries as they are located in temperate places (or even bene…cial e¤ects in cold climates); see, for instance, Burke et al. (2015), Dell et al. (2012), and Kalkuhl and Wenz 2020. An exception is a recent paper by Burke and Tanutama (2019). 3The upper bound of these losses allow for temperature increases to a¤ect the variability of temperature shocks commensurately. Accounting for transition risks (in addition to physical risks) would lead to larger losses (especially for advanced economies, see, for instance, Klusak et al. 2021 and Agarwala et al. 2021). 1 labour productivity, employment, and output growth in various sectors of the economy.4 Additionally, we contribute to the literature along the following dimensions. Firstly, we di¤erentiate between level and growth e¤ects and estimate the long-term macroeconomic impact of persistent increases in temperature and precipitation. Secondly, we use the half- panel Jackknife FE (HPJ-FE) estimator proposed in Chudik et al. (2018) to deal with the possible bias and size distortion of the commonly-used FE estimator. Thirdly, we depart from the literature in focusing on changes in the distribution of weather patterns (not only averages of temperature and precipitation but also their variability) and introducing an implicit model of adaptation. Fourthly, we allow for state-speci…c and time-varying climate thresholds— a subtle form of nonlinearity5— and also test for asymmetric weather e¤ects. Finally, we avoid the econometric pitfalls associated with the use of trended variables, such as temperature, in output growth equations (see Kahn et al. 2021b for details). Our within-country results provide evidence for the damage that climate change causes in the U.S. using various economic indicators at the state level: growth rates of Gross State Product (GSP), GSP per capita, labour productivity, and employment as well as output in di¤erent sectors (e.g., agriculture, manufacturing, services, retail and wholesale trade). We show that if temperature increases by 0:01C annually above its historical norm across U.S. states persistently, average per-capita real GSP growth will be lower by around 0:03 percentage points per year— a number that is smaller than those obtained in cross-country regressions of Kahn et al. (2021a). We show that the impact of climate change on sectoral output growth is broad based— each of the 10 sectors considered is a¤ected by at least one of the four climate variables. Moreover, in contrast to most cross-country results, the within U.S. estimates tend to be asymmetrical with respect to deviations of climate variables from their historical norms (in the positive and negative directions). Finally, while we acknowledge some resilience-building e¤orts in di¤erent states, the evidence seems to suggest that it has not entirely o¤set the negative e¤ects of climate change at the country level. The remainder of this paper is organized as follows. Section 2 presents the empirical results and Section 3 concludes. Appendix A lists the data sources and their compilation. 4There are likely economic spillovers across states in the form of migration by households and pro…t shifting by …rms to arbitrage di¤erences in cross-state regulatory regimes (tax systems and environmental standards) as well as varying degrees of climate risks, which are important for a model’s dynamics. See, for instance, Aquaro et al. (2021) for an example of how heterogeneous spillover e¤ects across regions can be investigated. However, this paper abstracts from such spillovers given its focus on the long-term (equilibrium) macroeconomic e¤ects of climate change. 5Non-linearity arises because growth is only a¤ected when temperature (or precipitation) goes above or below a time-varying and state-speci…c historical threshold (i.e., the norm). It is due to this feature that future growth is a¤ected not only by warming (or cooling if that was the case) but also by its variability. 2 2 Long-Run Impact of Climate Change on U.S. Eco- nomic Growth We …rst examine whether temperature across the 48 U.S. states has been increasing between 1963 and 2016. To this end, allowing for the signi…cant heterogeneity that exists across states with respect to changes in temperature over time, we estimate state-speci…c regressions Tit = aT i + bT it+ vT i;t; for i = 1; 2; :::; N = 48; (1) where Tit denotes the weighted average temperature of state i at year t. The per annum av- erage increase in land temperature for state i is given by bT i; with the corresponding country measure de…ned by bT = N1Ni=1bT i. Our results suggest that, on average, temperature in the 48 U.S. states has risen by 0:026 degrees Celsius (C) per year over 1963–2016 (i.e., b^T = 0:0260 (0:0007); with the standard error in brackets), with this trend estimate being statistically signi…cant at the 1% level. All states experienced statistically signi…cant in- creases in temperature over time (see Table 1). But, the 48 U.S. states as a whole underwent more warming than the world on average. The U.S. average per annum temperature increase of 0:026 was appreciably higher than the world average rise of 0:018 per annum, which is close to that for Oklahoma, the state which saw the lowest average increase in temperature. Table 1: Individual U.S. State Estimates of the Average Yearly Rise in Temper- ature Over the Period 1963–2016 State b^;i State b^;i State b^;i Alabama 0.0212z Maine 0.0288z Ohio 0.0263z Arizona 0.0318z Maryland 0.0299z Oklahoma 0.0171z Arkansas 0.0181z Massachusetts 0.0311z Oregon 0.0198z California 0.0270z Michigan 0.0285z Pennsylvania 0.0280z Colorado 0.0271z Minnesota 0.0320z Rhode Island 0.0320z Connecticut 0.0316z Mississippi 0.0205z South Carolina 0.0250z Delaware 0.0355z Missouri 0.0179z South Dakota 0.0234z Florida 0.0228z Montana 0.0292z Tennessee 0.0234z Georgia 0.0228z Nebraska 0.0222z Texas 0.0245z Idaho 0.0245z Nevada 0.0273z Utah 0.0291z Illinois 0.0223z New Hampshire 0.0299z Vermont 0.0318z Indiana 0.0236z New Jersey 0.0343z Virginia 0.0266z Iowa 0.0198z New Mexico 0.0300z Washington 0.0186z Kansas 0.0186z New York 0.0308z West Virginia 0.0268z Kentucky 0.0250z North Carolina 0.0257z Wisconsin 0.0307z Louisiana 0.0210z North Dakota 0.0263z Wyoming 0.0279z Notes: bbT i are the individual state-level estimates based on Tit = aT i + bT it + vT ;it, where Tit denotes the average temperature (C) in state i in year t. z indicates statistical signi…cance at the 1% level. We next examine the long-run impact of climate change on aggregate state-level economic 3 activity as well as states’ sectoral outputs. Such a within-country study is scant in the literature as priority is given to studying the impact of climate change on a particular sector of an economy (e.g., agricultural output) or to cross-country analyses. Guided by the theoretical growth model with weather and climate variables developed in Kahn et al. (2021a), we estimate the following panel ARDL model using the half-panel Jackknife FE (HPJ-FE) estimator of Chudik et al. (2018): yi;t = ai + pX l=1 lyi;tl + pX l=0 0l~xi;tl + i;t; (2) where yit is the log of real GSP of state i in year t or real GSP per capita, ~xit(m) = [ ~Tit (m) +, ~Tit (m) ; ~Pit (m) + ; ~Pit (m) ]0, ~Tit (m) =  Tit T i;t1(m)  and ~Pit (m) =  Pit P i;t1(m)  are measures of temperature and precipitation relative to their historical norms, Tit and Pit are the annual average temperature and precipitation of state i in year t, respectively, and T i;t1(m) = 1 m Pm `=1 Ti;t` and P  i;t1(m) = 1 m Pm `=1 Pi;t` are the time-varying historical norms of temperature and precipitation of state i over the preceding m years in each t. Climate norms are typically computed as 30-year moving averages (Arguez et al. 2012 and Vose et al. 2014), but to check the robustness of our results, we also consider historical norms with m = 20 and 40.6 With ~Tit (m) and ~Pit (m) separated into positive and negative values, we account for potential asymmetrical e¤ects of climate change on growth around the threshold. The (average) long-run e¤ects, i , are calculated from the OLS estimates of the short-run coe¢ cients in equation (2):  = 1 Pp `=0 `, where  = 1 Pp `=1 '`. Since temperature is trended across the sample of 48 U.S. states, its inclusion in the regression will introduce a linear trend in per capita output growth which is not supported by the data, and can lead to biased estimates. This is the reason for specifying ARDL growth regressions in deviations form (i.e., temperature and precipitation relative to their long-term moving average historical norms), rather than in levels and/or squares of climate variables.7 Other important econometric considerations behind the use of ARDL regressions are set out in Pesaran and Smith (1995), Pesaran (1997), and Pesaran and Shin (1999) who show that the traditional ARDL approach can be used for long-run analysis; it is valid regardless of whether the underlying variables are I (0) or I (1); and it is robust to omitted variables and bi-directional feedback e¤ects between economic growth and its determinants. These features of the panel ARDL approach are clearly appealing in our empirical application. For validity of this technique, however, the dynamic speci…cation of the model needs to be augmented with a su¢ cient number of lags so that regressors become weakly exogenous.8 Since we 6m = 30 corresponds to the o¢ cial World Meteorological Organization de…nition of climate (i.e., norm). 7For a detailed discussion see Kahn et al. (2021b), where it is shown that including Tit and T 2it in growth regressions will introduce trends in yit. 8See Chudik et al. (2013), Chudik et al. (2016), and Chudik et al. (2017) for details. 4 are interested in studying the growth e¤ects of climate change (a long-term phenomenon), the lag order should be long enough, and as such we set p = 4 for all the variables/states. Using the same lag order across all the variables and states avoids data mining that could accompany the use of state and variable speci…c lag order selection procedures such as Akaike or Schwarz criteria. Note also that our primary focus here is on the long-run estimates rather than the speci…c dynamics that might be relevant for a particular U.S. state. Table 2 reports the long-run estimates of weather shocks on growth rates of real GSP and real GSP per capita for 48 U.S. states over the period 1963–2016. We construct the climate variables with historical norms computed using 20, 30, and 40 years moving-averages, but consider the estimates based on the 30-year moving averages as our central estimates. We observe that the estimated long-run coe¢ cients b ~Tit(m) ; b ~Pit(m)+, and b ~Pit(m) are negative and statistically signi…cant in all cases except for one. Climate change a¤ects the U.S. ecosystem not only through increases in average temperatures, but also through changes in the extremes— more intense droughts; heavier snow and rainfall; as well as extreme cold. However, b ~Tit(m)+ is not statistically signi…cant in three out of six speci…cations. While this …nding might be explained by the improving resilience of the U.S. economy to increasing temperature brought by climate change,9 the evidence for excessive temperature not a¤ecting the U.S. economy is not conclusive as we will explain below. While in their cross-country analysis, Kahn et al. (2021a) did not …nd any statistically signi…cant impact from deviations of precipitation from its historical norms on output growth, in our within-country study of the United States, we …nd that deviations of precipitation above and below its historical norm a¤ect various measures of state-level economic activity and these estimates are statistically signi…cant.10 This is because averaging precipitation at the country level leads to a loss of information, especially in geographically diverse countries with varied precipitation patterns. While the national average precipitation may be close to its historical norm, there is signi…cant heterogeneity across states with some experiencing plenty of rain and snow and others, like California, su¤ering from drought for many years. By conducting a within-country study, we account for the variation of precipitation across the states, which is important and does indeed a¤ect economic activity (Table 2). Considering the richness of our U.S. database, which includes data on state-level em- ployment from 1976, we can also examine the long-run impact of climate change on labour productivity and employment growth directly, in addition to re-estimating the regressions over the period 1976–2016. We, therefore, re-estimate the model for an extended set of outcome variables, with yit being the natural logarithm of: (i) real GSP, (ii) real GSP per capita, (iii) real GSP per employed (measuring labour productivity), or (iv) employ- 9For example, currently about 90 percent of American households have air conditioning. 10The importance of focusing on deviations of climate variables from their historical norms is also high- lighted by recent research which demonstrate that di¤erent regions of the United States have acclimated themselves to their own temperature niche; see, for instance, Heutel et al. (2016). 5 T ab le 2: L on g- R u n E ¤ ec ts of C li m at e C h an ge on th e G ro w th R at e of M a jo r E co n om ic In d ic at or s fo r th e U n it ed S ta te s, 19 63 –2 01 6 H is to ri ca l N o rm : 2 0 Y ea r M A 3 0 Y ea r M A 4 0 Y ea r M A R ea l G S P R ea l G S P p er C ap it a R ea l G S P R ea l G S P p er C ap it a R ea l G S P R ea l G S P p er C ap it a b  ~ T i t (m )+ -0 .0 24 5* ** -0 .0 14 3* * -0 .0 15 2* * -0 .0 07 3 -0 .0 07 4 -0 .0 01 4 (0 .0 08 1) (0 .0 06 4) (0 .0 07 7) (0 .0 06 1) (0 .0 07 3) (0 .0 05 8) b  ~ T i t (m ) -0 .0 67 2* ** -0 .0 44 4* ** -0 .0 69 7* ** -0 .0 45 4* ** -0 .0 48 5* ** -0 .0 27 5* * (0 .0 16 2) (0 .0 12 4) (0 .0 16 6) (0 .0 12 4) (0 .0 16 9) (0 .0 12 7) b  ~ P i t (m )+ -0 .1 09 1* ** -0 .0 90 6* ** -0 .1 37 0* ** -0 .1 13 4* ** -0 .1 33 9* ** -0 .1 09 9* ** (0 .0 41 1) (0 .0 32 8) (0 .0 41 1) (0 .0 32 7) (0 .0 41 2) (0 .0 32 8) b  ~ P i t (m ) -0 .1 17 2* * -0 .0 65 1 -0 .1 47 7* ** -0 .0 92 8* * -0 .1 55 2* ** -0 .0 99 0* * (0 .0 50 9) (0 .0 41 1) (0 .0 52 9) (0 .0 42 4) (0 .0 55 8) (0 .0 44 9) b  0. 72 63 ** * 0. 88 96 ** * 0. 72 10 ** * 0. 88 75 ** * 0. 71 09 ** * 0. 87 34 ** * (0 .0 49 1) (0 .0 53 0) (0 .0 49 4) (0 .0 53 2) (0 .0 49 5) (0 .0 53 3) N o. of st at es (N ) 48 48 48 48 48 48 T 48 48 48 48 48 48 N  T 23 04 23 04 23 04 23 04 23 04 23 04 N ot es : T h e H P J- F E es ti m at es ar e b as ed on th e fo ll ow in g sp ec i… ca ti on  y i; t = a i + P p l= 1 l y i; t l + P p l= 0 0 l ~x i; t l +  i ;t , w h er e y it is th e lo g of re al G S P of st at e i in ye ar t or re al G S P p er ca p it a, ~x it (m ) = [ ~ T it (m )+ , ~ T it (m ) ; ~ P it (m )+ ; ~ P it (m ) ]0 , ~ T it (m ) = h T it T  i;t 1 (m )i an d ~ P it (m ) = h P it P  i;t 1 (m )i ar e m ea su re s of te m p er at u re an d p re ci p it at io n re la ti ve to th ei r h is to ri ca l n or m s, T it an d P it ar e th e an nu al av er ag e te m p er at u re (i n C el si u s) an d p re ci p it at io n (i n m et re s) of st at e i in ye ar t, re sp ec ti ve ly , an d T  i;t 1 (m ) = 1 m P m `= 1 T i; t ` an d P  i;t 1 (m ) = 1 m P m `= 1 P i; t ` ar e th e ti m e- va ry in g h is to ri ca l n or m s of te m p er at u re an d p re ci p it at io n of st at e i ov er th e p re ce d in g m ye ar s in ea ch t. T h e lo n g- ru n e¤ ec ts ,  i , ar e ca lc u la te d fr om th e O L S es ti m at es of th e sh or t- ru n co e¢ ci en ts in eq u at io n (2 ):  =  1 P p `= 0 ` , w h er e  = 1 P p `= 1 ' ` . T h e la g or d er , p , is se t to 4. S ta n d ar d er ro rs in p ar en th es es ar e es ti m at ed by th e es ti m at or p ro p os ed in P ro p os it io n 4 of C hu d ik et al . (2 01 8) . A st er is ks in d ic at e st at is ti ca l si gn i… ca n ce at 1% (* ** ), 5% (* *) , an d 10 % (* ) le ve ls . 6 ment, but over the period 1976 to 2016. These results are reported in Table 3. Across all speci…cations, the estimated long-run coe¢ cients b ~Tit(m) and b ~Pit(m) are negative and statistically signi…cant at the 1% level for almost all outcome variables. Therefore, when temperature and precipitation fall below their historical norms, state-level economic activity su¤ers, employment declines, and labour productivity growth falls (for b ~Tit(m)). While in Table 2, the climate variable ~Tit (m) +, did not have a statistically signi…cant impact on state-level output growth in three out of six speci…cations (over the period 1963– 2016), the results change substantially when we consider the 1976–2016 sub-sample in Table 3. Consistent with cross-country estimates, b ~Tit(m)+ is now negative and statistically sig- ni…cant for various speci…cations and dependent variables: real GSP, real GSP per capita, real GSP per employed, and employment. The size of the estimates for b ~Tit(m)+ is smaller in absolute value than those obtained in cross-country regressions of Kahn et al. (2021a), partly re‡ecting a higher degree of adaptation in the U.S. to climate change. Nonetheless, contrary to most studies in the literature, our estimates are not negligible. Our results are supported by Deryugina and Hsiang (2014) and Behrer and Park (2017), who exploit county- level variations in climate variables over time in the U.S. and …nd that hotter temperatures damage economic activity, and also by Colacito et al. (2019) who …nd that an increase in summer temperatures has adverse e¤ects on GSP growth in the United States. 2.1 Adaptation and the U.S. Economy While there is growing evidence of the bene…ts of climate-change adaptation at the sectoral and micro level, the macroeconometric-climate literature does not provide conclusive esti- mates of the economic bene…ts of adaptation. An exception is Kahn et al. (2021a) who …nd that adaptation has the potential to halve the long-term growth e¤ects of global warming. They model adaptation by assuming di¤erent speeds of the formation of historical norms. Their results hold in our within-country study of the U.S. states. Another way to assess adaptation is to test how the elasticity of growth to climate variables evolves over time. Speci…cally, if the U.S. economy were adapting to climate change, ceteris paribus, should we not expect the impact of deviations of temperature and precipitation from their historical norms to be shrinking over time? To investigate this hypothesis, we re-estimate the model over di¤erent time windows using real GSP per capita growth as the dependent variable. We start with the full sample, 1963–2016, and then drop a year at a time (with the last estima- tion being carried out for the sub-sample 1983–2016). The results are plotted in Figure 1, showing that the estimated coe¢ cients are becoming larger (in absolute value) over time. Do these results cast doubt on the e¢ cacy of adaptation e¤orts in the United States over the last …ve decades? Probably not. Ceteris paribus, while it is expected that adaptation weakens the relationship between climate change and economic growth over time, we cannot 7 T ab le 3: L on g- R u n E ¤ ec ts of C li m at e C h an ge on th e G ro w th R at e of M a jo r E co n om ic In d ic at or s fo r th e U n it ed S ta te s, 19 76 –2 01 6 H is to ri ca l N o rm : 2 0 Y ea r M A 3 0 Y ea r M A 4 0 Y ea r M A R ea l G S P R ea l G S P R ea l G S P E m p lo ym en t R ea l G S P R ea l G S P R ea l G S P E m p lo ym en t R ea l G S P R ea l G S P R ea l G S P E m p lo ym en t p er C ap it a p er E m p lo ye d p er C ap it a p er E m p lo ye d p er C ap it a p er E m p lo ye d b  ~ T i t (m )+ -0 .0 39 1* ** -0 .0 27 9* ** -0 .0 18 8* ** -0 .0 13 6* * -0 .0 37 9* ** -0 .0 27 3* ** -0 .0 19 0* ** -0 .0 13 5* * -0 .0 37 1* ** -0 .0 27 1* ** -0 .0 18 8* ** -0 .0 12 5* * (0 .0 10 8) (0 .0 08 4) (0 .0 06 7) (0 .0 06 5) (0 .0 10 7) (0 .0 08 3) (0 .0 06 7) (0 .0 06 2) (0 .0 10 5) (0 .0 08 2) (0 .0 06 5) (0 .0 06 2) b  ~ T i t (m ) -0 .1 55 4* ** -0 .1 19 9* ** -0 .0 60 4* ** -0 .0 72 3* ** -0 .1 95 1* ** -0 .1 50 5* ** -0 .0 77 9* ** -0 .0 95 4* ** -0 .2 08 9* ** -0 .1 61 6* ** -0 .0 84 7* ** -0 .1 02 7* ** (0 .0 31 5) (0 .0 23 3) (0 .0 16 6) (0 .0 18 3) (0 .0 35 8) (0 .0 25 9) (0 .0 19 1) (0 .0 20 5) (0 .0 38 8) (0 .0 28 3) (0 .0 20 7) (0 .0 22 1) b  ~ P i t (m )+ -0 .1 11 2* -0 .0 93 0* -0 .0 38 1 -0 .0 43 4 -0 .1 59 8* * -0 .1 34 5* ** -0 .0 44 3 -0 .0 85 3* * -0 .1 32 6* * -0 .1 12 0* * -0 .0 29 9 -0 .0 79 2* * (0 .0 63 0) (0 .0 50 0) (0 .0 39 0) (0 .0 40 9) (0 .0 63 4) (0 .0 49 8) (0 .0 39 5) (0 .0 39 5) (0 .0 61 3) (0 .0 48 4) (0 .0 38 5) (0 .0 38 7) b  ~ P i t (m ) -0 .2 84 0* ** -0 .1 98 1* ** -0 .0 51 0 -0 .2 08 2* ** -0 .3 40 7* ** -0 .2 41 2* ** -0 .0 55 3 -0 .2 51 5* ** -0 .3 51 5* ** -0 .2 50 3* ** -0 .0 53 0 -0 .2 76 3* ** (0 .0 78 1) (0 .0 60 0) (0 .0 44 3) (0 .0 55 3) (0 .0 83 7) (0 .0 62 8) (0 .0 46 7) (0 .0 59 4) (0 .0 87 8) (0 .0 66 5) (0 .0 49 0) (0 .0 63 6) b  0. 50 92 ** * 0. 63 27 ** * 0. 72 19 ** * 0. 43 71 ** * 0. 50 16 ** * 0. 63 01 ** * 0. 70 35 ** * 0. 43 82 ** * 0. 49 75 ** * 0. 62 15 ** * 0. 69 42 ** * 0. 42 90 ** * (0 .0 50 3) (0 .0 52 9) (0 .0 75 6) (0 .0 44 5) (0 .0 50 4) (0 .0 53 0) (0 .0 75 6) (0 .0 44 4) (0 .0 50 2) (0 .0 53 0) (0 .0 74 9) (0 .0 44 5) N o. of st at es (N ) 48 48 48 48 48 48 48 48 48 48 48 48 T 36 36 36 36 36 36 36 36 36 36 36 36 N  T 17 28 17 28 17 28 17 28 17 28 17 28 17 28 17 28 17 28 17 28 17 28 17 28 N ot es : T h e H P J- F E es ti m at es ar e b as ed on th e fo ll ow in g sp ec i… ca ti on  y i; t = a i + P p l= 1 l y i; t l + P p l= 0 0 l ~x i; t l +  i ;t , w h er e y it is th e lo g of (i ) re al G S P , (i i) re al G S P p er ca p it a, (i ii ) re al G S P p er em p lo ye d , an d (i v ) em p lo ym en t of st at e i in ye ar t, ~x it (m ) = [ ~ T it (m )+ , ~ T it (m ) ; ~ P it (m )+ ; ~ P it (m ) ]0 , ~ T it (m ) = h T it T  i;t 1 (m )i an d ~ P it (m ) = h P it P  i;t 1 (m )i ar e m ea su re s of te m p er at u re an d p re ci p it at io n re la ti ve to th ei r h is to ri ca l n or m s, T it an d P it ar e th e an nu al av er ag e te m p er at u re (i n C el si u s) an d p re ci p it at io n (i n m et re s) of st at e i in ye ar t, re sp ec ti ve ly , an d T  i;t 1 (m ) = 1 m P m `= 1 T i; t ` an d P  i;t 1 (m ) = 1 m P m `= 1 P i; t ` ar e th e ti m e- va ry in g h is to ri ca l n or m s of te m p er at u re an d p re ci p it at io n of st at e i ov er th e p re ce d in g m ye ar s in ea ch t. T h e lo n g- ru n e¤ ec ts ,  i , ar e ca lc u la te d fr om th e O L S es ti m at es of th e sh or t- ru n co e¢ ci en ts in eq u at io n (2 ):  =  1 P p `= 0 ` , w h er e  = 1 P p `= 1 ' ` . T h e la g or d er , p , is se t to 4. S ta n d ar d er ro rs in p ar en th es es ar e es ti m at ed by th e es ti m at or p ro p os ed in P ro p os it io n 4 of C hu d ik et al . (2 01 8) . A st er is ks in d ic at e st at is ti ca l si gn i… ca n ce at 1% (* ** ), 5% (* *) , an d 10 % (* ) le ve ls . 8 Figure 1: Long-Run E¤ects of Climate Change on per capita Real GSP Growth in the United States, 1963–2016 Notes: Figures show the long-run e¤ects (and their 95% standard error bands) of climate change on state- level economic growth in the United States over di¤erent windows, using the ARDL speci…cation (2). We start the estimation with the full sample (1963–2016) and then drop one year at a time, ending with the …nal estimates based on the 1983–2016 sub-sample. 9 conclude that the U.S. economy has not been adapting to climate change based on Figure 1. First, adaptation e¤orts might be concentrated in certain sectors. Second, it may be the case that adaptation is not keeping pace with climate change; i.e., global temperatures have increased at an unprecedented pace over the past 40 years. Third, the e¤ects of adaptation might have been o¤set by structural changes to the U.S. economy (that is a shift of value added to sectors that are more exposed to climate change). Fourth, if …rms underestimate the likelihood or severity of future weather events, they may not adapt su¢ ciently; i.e., adap- tation technologies are readily available but the take-up is limited by …rms. In a survey of private sector organizations across multiple industries within the Organization for Economic Cooperation and Development (OECD) countries, Agrawala et al. (2011) …nd that only few …rms have taken su¢ cient steps to assess and manage the risks from climate change. Fifth, according to Deryugina and Hsiang (2014) …rms tend to under-invest in adaptation owing to its high cost.11 We argue that there has been some adaptation in the U.S. given that the estimates in Tables 2 and 3 are generally smaller than those obtained in the cross- country study of Kahn et al. (2021a) and they are increasing with m (if expressed in per annum terms)— i.e., the faster is the change in historical norms, the less is the size of income losses across U.S. states. However, the evidence suggests that adaptation e¤orts should be complemented with mitigation policies to minimize the adverse e¤ects of climate change. 2.2 Further Evidence from U.S. Sector Level Data Adaptation and mitigation can occur in the short-term through a reallocation of resources, and in the long-term through investment in research and development, innovation, or a shift in the economic structure of the country towards an industry mix that is less vulnerable to climate change. Given that adaptation is relatively easier and more e¤ective to implement in some industries than others, we …rst need to assess which sectors/industries are more likely to be a¤ected by climate change in the U.S. economy. Focusing on di¤erent sectors/industries also helps shed light on the channels through which climate change a¤ects the United States economy. We consider ten sectors, and due to lack of worker per sector data at the state level, we only report the results for state-level output growth.12 The long-run sectoral e¤ects of climate change estimated on the panel of the 48 U.S. states over the period 1963–2016 are reported in Table 4. The estimates show that the impact is broad based— each of the 10 sectors is a¤ected by at least one of the four climate variables. Speci…cally, the agricultural sector is negatively impacted by a rise in temperature above its historical norm, b ~Tit(m)+ < 0. In addition, precipitation above and below the norm also exert negative e¤ects on agricultural output growth. These results are in line with the 11For a discussion of costs associated with diverting funds away from productive capital, see Mohaddes and Williams (2020). Other reasons for underinvestment include knowledge spillovers and networks externalities. 12See Appendix A for further details. 10 …ndings of Burke and Emerick (2016), who consider corn and soy farming in the U.S. over the period 1955–2005, and …nd that, despite some adaptation e¤orts by farmers, agricultural output is damaged by extreme heat and excessive precipitation. Note also that the cost of adaptation to climate change is high in the agricultural sector— constructing greenhouses or varying crop mixes involves heftier investments than …tting air conditioning units in o¢ ces. Table 4 also illustrates that deviations of all four climate variables from their historical norms have adverse e¤ects on output growth in the manufacturing sector. While the negative impact of climate change on agricultural production is well studied, the adverse e¤ects on the manufacturing sector in the United States are only being discussed in the new climate economy literature (using micro-data analyses). For example, Cachon et al. (2012) use weekly production data from 64 automobile plants in the U.S. and …nd that climate variations (extensive periods of rain and snow, high heat, and severe winds), lead to costly production volatility, and have adverse e¤ects on labour productivity, in line with our results. Moreover, our estimates show that output growth in mining, construction, transport, retail trade, wholesale trade, services and government sectors are all negatively a¤ected by unusually cold days in the U.S. as consumer spending falls (households may delay shopping or even cut from spending owing to higher heating costs or home-repair expenses); supply chains are interrupted;13 and construction projects are delayed. See also Bloesch and Gourio (2015) for further supporting evidence. Heavy rain can also reduce access to mountainous mining regions, where large deposits are generally found, thereby reducing output growth in the mining sector. Construction and transportation activities are also a¤ected by rain/snow. Most discussions of climate change focus on the expected increase in average global temperatures over the next century (i.e. global warming). However, the frequency and severity of weather events (such as heat or cold waves, droughts and ‡oods, as well as natural disasters) depend heavily on the variability of temperatures and precipitation as well as their mean. The larger the swings, the more often extremely hot or cold and wet or dry conditions can wreak havoc; see, for instance, Swain et al. 2018. Given current projections of rising average global temperature over the next century, the likelihood that temperatures persistently drift above their historical norm is very high. As we showed above, this could lead to a permanent negative impact on state-level output growth (that is lower production growth in all sectors of the United States economy apart from the mining, government, and …nance, insurance and real estate sectors). While persistent deviations of precipitation from its historical norm (either above and below) or below-the-norm temperatures are less likely, the swings (variability) could be unprecedentedly large owing to climate change, and hence, the negative impact on state-level output growth could be sizable and long lasting. Overall, the industry-level results in Table 4 and the state-level results in Tables 2– 13For example, steel production along the coast of Lake Michigan was majorly disrupted during the brutal 2013-14 winter, because frozen Great Lakes meant that cargoes could not be moved via boats as usual. 11 T ab le 4: L on g- R u n E ¤ ec ts of C li m at e C h an ge on th e O u tp u t G ro w th of V ar io u s S ec to rs in th e U n it ed S ta te s, 19 63 –2 01 6 A gr ic u lt u re T ra n sp or t F in an ce F or es tr y M in in g C on st ru ct io n M an u fa ct u ri n g C om m u n ic at io n W h ol es al e T ra d e R et ai l T ra d e In su ra n ce S er vi ce s G ov er n m en t F is h er ie s P u b li c U ti li ti es R ea l E st at e b  ~ T i t (m )+ -0 .0 32 3* -0 .0 03 0 -0 .0 58 7* ** -0 .0 66 6* ** -0 .0 26 1* * -0 .0 62 8* ** -0 .0 53 1* ** 0. 07 30 ** * -0 .0 33 6* ** 0. 01 82 * (0 .0 17 8) (0 .0 40 0) (0 .0 20 4) (0 .0 16 3) (0 .0 11 2) (0 .0 20 9) (0 .0 12 6) (0 .0 16 1) (0 .0 11 0) (0 .0 10 7) b  ~ T i t (m ) -0 .0 18 4 -0 .1 88 7* ** -0 .1 77 7* ** -0 .1 13 6* ** -0 .0 63 3* ** -0 .2 36 5* ** -0 .1 67 4* ** 0. 00 50 -0 .1 20 1* ** -0 .0 44 6* * (0 .0 31 5) (0 .0 72 8) (0 .0 40 0) (0 .0 27 0) (0 .0 17 5) (0 .0 38 9) (0 .0 23 7) (0 .0 30 9) (0 .0 25 2) (0 .0 19 9) b  ~ P i t (m )+ -0 .3 05 4* ** -0 .6 05 2* ** -0 .2 16 4* * -0 .2 38 2* ** 0. 13 40 ** -0 .0 91 7 -0 .0 71 1 -0 .0 24 2 -0 .1 18 2* 0. 00 00 (0 .0 82 6) (0 .2 16 1) (0 .1 06 9) (0 .0 79 2) (0 .0 54 7) (0 .1 11 5) (0 .0 66 0) (0 .0 80 3) (0 .0 63 5) (0 .0 55 5) b  ~ P i t (m ) -0 .5 49 9* ** -0 .2 97 3 -0 .2 00 0 -0 .2 68 9* ** -0 .1 02 2 -0 .2 98 7* * -0 .2 39 0* ** 0. 04 62 -0 .1 31 7* 0. 01 84 (0 .1 18 8) (0 .2 88 4) (0 .1 34 4) (0 .1 01 9) (0 .0 68 5) (0 .1 31 2) (0 .0 84 6) (0 .1 01 3) (0 .0 77 2) (0 .0 78 7) b  1. 88 92 ** * 0. 81 33 ** * 0. 64 12 ** * 0. 95 99 ** * 0. 85 36 ** * 0. 48 30 ** * 0. 57 87 ** * 0. 59 44 ** * 0. 41 35 ** * 0. 39 02 ** * (0 .0 84 3) (0 .0 45 9) (0 .0 33 1) (0 .0 72 6) (0 .0 58 1) (0 .0 39 4) (0 .0 31 2) (0 .0 54 6) (0 .0 41 4) (0 .0 45 8) N o. of st at es (N ) 48 47 48 48 48 48 48 48 48 48 T 48 48 48 48 48 48 48 48 48 48 N  T 23 04 22 56 23 04 23 04 23 04 23 04 23 04 23 04 23 04 23 04 N ot es : T h e H P J- F E es ti m at es ar e b as ed on th e fo ll ow in g sp ec i… ca ti on  y i; t = a i + P p l= 1 l y i; t l + P p l= 0 0 l~x i; t l +  i ;t , w h er e y it is th e lo g of se ct or al re al ou tp u t in st at e i in ye ar t, ~x it (m ) = [ ~ T it (m )+ , ~ T it (m ) ; ~ P it (m )+ ; ~ P it (m ) ]0 , ~ T it (m ) = h T it T  i;t 1 (m )i a n d ~ P it (m ) = h P it P  i;t 1 (m )i a re m ea su re s of te m p er at u re an d p re ci p it at io n re la ti ve to th ei r h is to ri ca l n or m s, T it an d P it ar e th e an nu al av er ag e te m p er at u re (i n C el si u s) an d p re ci p it at io n (i n m et re s) of st at e i in ye ar t, re sp ec ti ve ly , an d T  i;t 1 (m ) = 1 m P m `= 1 T i; t ` an d P  i;t 1 (m ) = 1 m P m `= 1 P i; t ` ar e th e ti m e- va ry in g h is to ri ca l n or m s of te m p er at u re an d p re ci p it at io n of st at e i ov er th e p re ce d in g m ye ar s in ea ch t (w it h m = 3 0 in th is ca se ). T h e lo n g- ru n e¤ ec ts ,  i , ar e ca lc u la te d fr om th e O L S es ti m at es of th e sh or t- ru n co e¢ ci en ts in eq u at io n (2 ):  =  1 P p `= 0 ` , w h er e  = 1 P p `= 1 ' ` . T h e la g or d er , p , is se t to 4. S ta n d ar d er ro rs in p ar en th es es ar e es ti m at ed by th e es ti m at or p ro p os ed in P ro p os it io n 4 of C hu d ik et al . (2 01 8) . A st er is ks in d ic at e st at is ti ca l si gn i… ca n ce at 1% (* ** ), 5% (* *) an d 10 % (* ) le ve ls . 12 3, show that deviations of temperature below its historical norms in the U.S. as well as deviations of precipitation from its historical norm are detrimental to long-run state-level and industry-level output growth. When it comes to deviations of temperature above its historical norms, the estimates are negative and statistically signi…cant at the aggregate state-level (in the more recent sample) and for all economic sectors apart from mining, government, and …nance, insurance and real estate sectors. In fact b ~Tit(m)+ is positive and statistically signi…cant for government services (at the 10% level) and …nance, insurance and real estate sectors, but most likely this re‡ects government spending on relief measures and higher insurance premiums in response to climate change. We acknowledge some resilience building activities in advanced economies, but the ev- idence from our U.S. within-country study seems to suggest that while adaptation might have reduced the negative e¤ects in certain sectors, it has not completely o¤set them at the macro level (see Table 3 and Figure 1). Behrer and Park (2017) note that even the most well-adapted regions in the United States su¤er negative production e¤ects from hotter tem- peratures and Colacito et al. (2019) show that an increase in average summer temperatures will have negative e¤ects on nominal output in various sectors, such as agriculture, construc- tion, retail, services, and wholesale trade. 3 Concluding Remarks Using data on 48 U.S. states from 1963 to 2016, and a novel econometric strategy (that di¤erentiates between level and growth e¤ects including in the long term; accounts for bi- directional feedbacks between growth and climate change; considers asymmetric weather e¤ects; allows for nonlinearity and an implicit model of adaptation; and deals with temper- ature being trended), we provided evidence for the damage that climate change causes in the U.S. using GSP, GSP per capita, labour productivity, and employment as well as output growth in ten economic sectors (such as agriculture, construction, manufacturing, services, retail and wholesale trade). While certain sectors in the U.S. economy might have adapted to higher temperatures, economic activity in the U.S. overall and at the sectoral level continues to be sensitive to deviations of temperature and precipitation from their historical norms. References Agarwala, M., M. Burke, P. Klusak, K. Mohaddes, U. Volz, and D. Zenghelis (2021). Climate Change and Fiscal Sustainability: Risks and Opportunities. National Institute Economic Review 258, 28–46. Agrawala, S., M. Carraro, N. Kingsmill, E. Lanzi, M. Mullan, and G. Prudent-Richard (2011). Private Sector Engagement in Adaptation to Climate Change: Approaches to Managing Climate Risks. OECD Environment Working Papers No 39 . 13 Aquaro, M., N. Bailey, and M. H. Pesaran (2021). Estimation and Inference for Spatial Models with Heterogeneous Coe¢ cients: An Application to US House Prices. Journal of Applied Econometrics 36 (1), 18–44. Arguez, A., I. Durre, S. Applequist, R. S. Vose, M. F. Squires, X. Yin, R. R. Heim, and T. W. Owen (2012). NOAA’s 1981-2010 U.S. Climate Normals: An Overview. Bulletin of the American Meteorological Society 93 (11), 1687–1697. Behrer, P. and J. Park (2017). Will We Adapt? Temperature Shocks, Labor and Adaptation to Climate Change. Working Paper . Bloesch, J. and F. Gourio (2015). The E¤ect of Winter Weather on U.S. Economic Activity. Economic Perspectives, Federal Reserve Bank of Chicago 39 (1), 1–20. Burke, M. and K. Emerick (2016). Adaptation to Climate Change: Evidence from US Agriculture. American Economic Journal: Economic Policy 8 (3), 106–140. Burke, M., S. M. Hsiang, and E. Miguel (2015). Global Non-Linear E¤ect of Temperature on Economic Production. Nature 527, 235–239. Burke, M. and V. Tanutama (2019). Climatic Constraints on Aggregate Economic Output. Working Paper 25779, National Bureau of Economic Research Working Paper 25779. Cachon, G. P., S. Gallino, and M. Olivares (2012). Severe Weather and Automobile Assembly Productivity. Columbia Business School Research Paper No. 12/37 . Chudik, A., K. Mohaddes, M. H. Pesaran, and M. Raissi (2013). Debt, In‡ation and Growth: Robust Esti- mation of Long-Run E¤ects in Dynamic Panel Data Models. Federal Reserve Bank of Dallas, Globalization and Monetary Policy Institute Working Paper No. 162 . Chudik, A., K. Mohaddes, M. H. Pesaran, and M. Raissi (2016). Long-Run E¤ects in Large Heterogeneous Panel Data Models with Cross-Sectionally Correlated Errors. In R. C. Hill, G. Gonzalez-Rivera, and T.- H. Lee (Eds.), Advances in Econometrics (Volume 36): Essays in Honor of Aman Ullah, Chapter 4, pp. 85–135. Emerald Publishing. Chudik, A., K. Mohaddes, M. H. Pesaran, and M. Raissi (2017). Is There a Debt-threshold E¤ect on Output Growth? Review of Economics and Statistics 99 (1), 135–150. Chudik, A., M. H. Pesaran, and J.-C. Yang (2018). Half-Panel Jackknife Fixed E¤ects Estimation of Panels with Weakly Exogenous Regressors. Journal of Applied Econometrics 33 (6), 816–836. Colacito, R., B. Ho¤mann, and T. Phan (2019). Temperature and Growth: A Panel Analysis of the United States. Journal of Money, Credit and Banking 51, 313–368. Dell, M., B. F. Jones, and B. A. Olken (2012). Temperature Shocks and Economic Growth: Evidence from the Last Half Century. American Economic Journal: Macroeconomics 4 (3), 66–95. Deryugina, T. and S. M. Hsiang (2014). Does the Environment Still Matter? Daily Temperature and Income in the United States. NBER Working Paper No. 20750 . Heutel, G., N. Miller, and D. Molitor (2016). Adaptation and the Mortality E¤ects of Temperature across US Climate Regions. NBER Working Paper No. 23271 . IPCC, . (2014). Climate Change 2014: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Volume 1. Cambridge University Press, Cambridge. 14 Kahn, M. E., K. Mohaddes, R. N. Ng, M. H. Pesaran, M. Raissi, and J.-C. Yang (2021a). Long-term Macroeconomic E¤ects of Climate Change: A Cross-country Analysis. Energy Economics 104, 105624. Kahn, M. E., K. Mohaddes, R. N. Ng, M. H. Pesaran, M. Raissi, and J.-C. Yang (2021b). Long-term Macroeconomic E¤ects of Climate Change: A Cross-country Analysis: Appendix A –Theory (A1), Relation to Literature (A2), Temperature Trends (A3), and Individual Country Results (A4). Energy Economics 104, 105624. Kalkuhl, M. and L. Wenz (2020). The Impact of Climate Conditions on Economic Production. Evidence From A Global Panel of Regions. Journal of Environmental Economics and Management 103, 102360. Klusak, P., M. Agarwala, M. Burke, M. Kraemer, and K. Mohaddes (2021). Rising Temperatures, Falling Ratings: The E¤ect of Climate Change on Sovereign Creditworthiness. Cambridge Working Papers in Economics 2127 . Kort, J. R. (2001). The North American Industry Classi…cation System in BEA’s Economic Accounts. Survey of Current Business. Mohaddes, K. and R. J. Williams (2020). The Adaptive Investment E¤ect: Evidence from Chinese Provinces. Economics Letters 193, 109332. Pesaran, M. H. (1997). The Role of Economic Theory in Modelling the Long Run. Economic Journal 107, 178–191. Pesaran, M. H. and Y. Shin (1999). An Autoregressive Distributed Lag Modelling Approach to Cointegra- tion Analysis. In S. Strom (Ed.), Econometrics and Economic Theory in 20th Century: The Ragnar Frisch Centennial Symposium, Chapter 11, pp. 371–413. Cambridge: Cambridge University Press. Pesaran, M. H. and R. Smith (1995). Estimating Long-run Relationships from Dynamic Heterogeneous Panels. Journal of Econometrics 68 (1), 79–113. Swain, D. L., B. Langenbrunner, J. D. Neelin, and A. Hall (2018). Increasing Precipitation Volatility in Twenty-…rst-century California. Nature Climate Change 8 (5), 427–433. Vose, R. S., S. Applequist, M. Squires, I. Durre, M. J. Menne, C. N. Williams, C. Fenimore, K. Gleason, and D. Arndt (2014). Improved Historical Temperature and Precipitation Time Series for U.S. Climate Divisions. Journal of Applied Meteorology and Climatology 53 (5), 1232–1251. 15 A Data Appendix We obtain state-level economic activity data from the Bureau of Economic Analysis (BEA). Real Gross State Product (GSP) data is available from 1977, but nominal GSP data is available from 1963. We de‡ate the nominal GSP series using the consumer price index (CPI) for each state, and splice the resulting data over 1963–1977 with the real GSP from 1977 using annual growth rates, to construct a real GSP series for 1963–2016. BEA provides output by sector at the state level from 1963. However, there are two issues with this database. Firstly, there was a change in industrial classi…cations in 1997: from 1963 to 1997, the Standard Industrial Classi…cation (SIC) consists of ten divisions, while from 1997 onwards, the North American Industry Classi…cation System (NAICS) gradually replaces the SIC, further branching the ten divisions into …fteen sectors.14 Secondly, as with the GSP data, only nominal sectoral output data (by SIC divisions) is available before 1977. Real sectoral output is available in both SIC and NAICS classi…cation in 1997. This allows us to construct the real sectoral output series from 1963–2016. Speci…cally, building a series over the period 1963 to 2016 involves two steps: (i) reconciling SIC and NAICS classi…cations (see Table A.1), and (ii) splicing the most recent real series (1997–2016) backwards using growth rates from the de‡ated nominal series (1963–1997). Table A.1: Division (SIC) and Sector (NAICS) Classi…cations Division (SIC) Sector (NAICS) Agriculture, Forestry, Fisheries Agriculture, Forestry, Fishing & Hunting Mining Mining Construction Construction Manufacturing Manufacturing Transportation & Warehousing Transport, Communication, and Public Utilities Information Utilities Wholesale Trade Wholesale Trade Retail Trade Retail Trade Finance, Insurance, and Real Estate Finance/Insurance/Real Estate/Rental/Leasing Professional & Business Services Services Educational Services/Health Care/Social Assistance Arts/Entertainment/Recreation/Accommodation/Food Services Other Services, Ex Government Government Government We use BEA’s producer price index (PPI) data to de‡ate the nominal industry outputs under SIC for the years 1963–1976. As the PPI data is constructed based on NAICS, we use the SIC- NAICS matching in Table A.1 for the PPI de‡ator. Where there is more than one NAICS sector matched to a SIC division, we take a simple arithmetic average of the PPI of all matched NAICS sectors. From 1997 onwards, real output by sector is available based on NAICS classi…cation. We, therefore, aggregate the NAICS real output by industry to SIC divisions using our matching scheme, and splice these series backwards using the growth rates of real sectoral output under SIC in 1963–1997. This gives us real output by sector and state for the period 1963 to 2016.15 14See Kort (2001) for more details. 15Note that "Agriculture, Forestry, Fishing & Hunting" and "Mining" data is not available for Rhode 16 We collect monthly state-level, area-weighted climate data from the NOAA’s National Centres for Environmental Information (NCEI). The NCEI reports monthly average temperature and pre- cipitation16 for each state from aggregates of climate readings across weather stations, adjusting for the distribution of stations and terrain. Temperature is measured in degrees Fahrenheit and pre- cipitation in inches. We convert them into degrees Celsius and metres, respectively. The monthly averages in each year within the sample period are then used to obtain annual averages. Finally, we obtain U.S. employment data from the Bureau of Labor Statistics (BLS). We take annual, state-level number of employed persons that encompasses "persons 16 years and over in the civilian noninstitutional population" under a wide range of employment conditions. Island in 2016 and agricultural data in 2016 is also unavailable for Delaware. Moreover, the mining industry of Delaware is excluded from our sample due to multiple irregular missing entries. 16Snow is included as melted precipitation in rain gauges under NOAA methodology. 17