TCS Daily

"Kinds of Weather"

By Willie Soon - October 6, 2003 12:00 AM

"I reverently believe that the Maker who made us all makes everything in New England but the weather. I don't know who makes that ... Old Probabilities has a mighty reputation for accurate prophecy, and thoroughly deserves it. You take up the paper and observe how crisply and confidently he checks off what to-day's weather is going to be on the Pacific, down South, in the Middle States, in the Wisconsin region. See him sail along in the joy and pride of his power till he gets to New England, and then see his tail drop. He doesn't know what the weather is going to be in New England."


-- Mark Twain's "Speech on the Weather" given at the New England Society's 71st annual dinner in New York City on December 22, 1876.


During the same dinner speech, Mark Twain observed that he was able to count 136 different "kinds of weather" in a single spring day.  This underscores the complex nature of the weather in New England.


But what has been the historical trend in air temperatures in New England?


This question is both timely and especially important when the governors of the states in New England have vowed to commit their citizens to drastic reductions in greenhouse gas (GHG) emissions.  Their Climate Change Action Plan proposes to reduce emissions to 1990 levels by 2010 and to 10% below 1990 levels by 2020 with an eventual cut to 75-85% below current levels "to eliminate any dangerous threat to the climate" (page 7 of their Climate Change Action Plan report). 


Following this lead, David Cohen and Timothy P. Murray, Mayors of Newton and Worcester, MA, respectively, co-authored an op-ed piece for the Boston Globe where they argued "the scientific community has come to a consensus that a 75-85 percent reduction in greenhouse gases is necessary." 


A response by Dr. Dick Lindzen, Professor at MIT and resident of Newton, MA, correctly points out the fallacy of these misguided statements -- namely, that such a drastic reduction literally means a return to the level of atmospheric carbon dioxide that accompanied the ice age some 21,000 years ago when New England was layered under mile-thick ice! This, of course, raises another important question: "Do these politicians really understand the problem well enough to lead policy formulation?"


In this ChartiFact, we address the factual evidence for any significant contemporary warming of the New England States by GHG emissions from the most reliable dataset available.




Figure 1:  Estimates of the 70-year temperature trend (1931-2000) for the fifteen climate divisions in New England.  Data are from the United States Historical Climate Network.  Overall, the warming is merely 0.4°C (0.7°F) for all 70 years or about 0.06°C (0.1°F) per decade.  Also note that only six of the fifteen New England climate divisions yield a statistically significant warming trend (the southeastern climate divisions marked with squared-boxes) despite the rapid increases in greenhouse gases. This warming trend is at variance with results derived by the United States National Assessment Synthesis Team Overview report (see Figure 2). [Figure adapted from Keim et al., 2003, Geophysical Research Letters, vol. 30, no. 7, 1404]



Figure 2: The 20th century observed (top) and 21st century model projected (Canadian Climate Centre, left, and the Hadley Centre, right, climate models) temperature trends for the Northeastern United States as reported by the United States National Assessment Synthesis Team Overview report (2000: p. 41).  The Hadley Centre model simulates an average warming of the Northeast by 2.6°C (or 5°F) for the 21st century while the Canadian Climate Centre model predicted a larger average warming of 5°C (or 9°F).  The observed 20th century warming trend reaching up to 2°C (4°F) along the coastal region of the Northeastern United States is not confirmed by the USHCN results shown in Figure 1.


Air temperature trends from 1931 to 2000 are shown in Figure 1 for the fifteen climate divisions in New England.  This figure is from a paper by Dr. Barry Keim and his colleagues at the University of New Hampshire and the United States Geological Survey based in Maine that recently was published in the prestigious journal Geophysical Research Letters.  They used data from the United States Historical Climate network (USHCN), which is considered to be the most reliable dataset available for evaluating historical trends in air temperature. 


Figure 1 makes several key points that raise serious questions regarding the basis for claims of a changing climate in New England and the policies proposed by the Governors of the New England states to mitigate those changes:


(1)   Only six of the fifteen New England climate divisions have experienced a statistically significant warming trend over the past seventy years (the five southeastern climate divisions marked with squared-boxes in Figure 1), despite the significant rise in GHG emissions during this time period.  However, this pattern is inconsistent with the trend -- up to 0.2°C (0.4°F) per decade and higher along the coast -- presented by the United States National Assessment Synthesis Team Overview and Foundation reports (2000, 2001) as shown in the upper image in Figure 2.  Note the pattern of warming in Figure 1 also contains more spatial non-uniformity than the consistent warming trend depicted by the National Assessment Synthesis Team in Figure 2.


(2)   The average warming trend for all of New England was 0.4°C (0.7°F) for the entire seventy-year period from 1931 to 2000 -- or a rate of about 0.06°C (0.1°F) per decade.  This rate of warming, however, is less than one quarter of the predicted warming rate in the Northeastern United States that may result from increased GHG emissions.  The National Assessment Synthesis Team report (2001, p. 113) suggests a warming of 0.3°C (0.5°F) to 0.5°C (0.9°F) per decade will occur over this century.


(3)   The USHCN database is a high-quality collection of monthly averaged air temperature and precipitation records that were selected by the National Climatic Data Center to assist in the detection of regional climate change.  But the number of stations within each climate division is extremely limited.  Almost half of the climate division analyses are based only on one or two stations (see Figure 1).  Other more comprehensive datasets exist but the inclusion of additional station records, often adversely affected by data inconsistencies, leads to estimates of insignificant warming or even cooling for the fifteen climate divisions over the last seventy years (see Figure 1 of Keim et al. 2003).


The disparity between the observed rates of increase as presented by the National Assessment Synthesis Team and those of Keim et al. leads one to question where the National Assessment obtained their data and why they did not use the high-quality USHCN dataset, which does not show significant warming in two-thirds of the climate divisions.


While we applaud the goals of the Governors of the New England States in their attempt to better manage the environmental impacts of human activity, it is as yet unclear what their proposed cuts in GHG emissions will achieve.  Reductions in emissions, even drastic ones, are unlikely to have significant local effects due to the global nature of the climate system.  But more importantly, their misguided efforts to eventually reduce GHG concentrations by 75-85% of present levels show a serious lack of scientific understanding.1 Should we then trust the New England governors to be leaders in policy-making?


Questions about other climate-related changes and their either harmful or beneficial effects are even more challenging although many simple-minded estimates have certainly been made. But based on the data showing current trends in the air temperature of New England, it is highly premature to commit to such drastic mitigation policies as has been proposed by the Governors of the New England States.




[1] As explained in both Professor Dick Lindzen's letter published on TCS and existing literature, the mitigation proposals usually call for a reduction in the emissions of GHG in order to hope for the stabilization of greenhouse gases in the atmosphere at a desirable (but scientifically arbitrary) level or concentration (for atmospheric carbon dioxide, future concentration levels ranging from 450 ppm to 1000 ppm have all been enumerated). The origin of such mitigation proposals is rooted in the Article 2 of the United Nations Framework Convention on Climate Change that has the ultimate objective in the "stabilization of greenhouse gas concentrations in the atmosphere at a level that will prevent dangerous interference with the climate system." (p. 54 of the Technical Summary of Climate Change 2001: Mitigation report)

TCS Daily Archives