Mean global temperatures have again reached new record-highs, in the latest instances for September and for January-September, according to the latest data and monthly report from the U.S. National Oceanic & Atmospheric Administration (NOAA).
September’s average temperature across both land and ocean came in at 1.62°F (0.9°C) above the the 20th century average.  That’s 0.12°F (0.19°C) above the previous record, which was set last year, NOAA highlighted. Last month’s record-high was also the highest in NOAA’s 136-year historical record, surpassing the previous record-high, which was set this February and March, by 0.02°F (0.01°C).
In other climate related research, a new study published in the October 21 online edition of Nature concluded that at the current rate, Â global warming is likely to reduce worldwide economic output more than has been projected over the course of the 21st century, with countries in warmer parts of the world set to bear the worst declines.
The effects of climate warming on national economies
Economies of countries in cooler climate zones are likely to experience improved conditions, at least initially, according to the study, which was produced by researchers at Stanford and the University of California, Berkeley. Richer countries in temperate zones, such as the U.S., are likely to experience brief upticks in national economic output before a threshold is hit and output drops sharply over the course of this century, according to a Stanford News Service report.
Researchers anticipate an overall drop in economic output out to 2100. Economic activity in countries in the tropics, most of which are considered ¨developing¨ or ¨lesser developed,¨ are projected to suffer the biggest declines.
“The data tell us that there are particular temperatures where we humans are really good at producing stuff,” Marshall Burke, the Stanford professor of Earth system science who co-led the research effort. “In countries that are normally quite cold – mostly wealthy northern countries – higher temperatures are associated with faster economic growth, but only to a point. After that point, growth declines rapidly.” That point, according to the research, turns out to be 55°F (12.78°C).
The research team studied records from 166 countries over a 50-year period from 1960-2010, comparing economic output in years with normal temperatures to those during which it was unusually warm or cold. The result was a ¨hill-shaped¨ relationship between temperature and economic output, with output rising up to 55°F and then declining at faster and faster rates as temperatures rose.
“Many very careful studies show clearly that high temperatures are bad for things like agriculture and labor productivity, even in rich countries,” Burke was quoted. “While these relationships showed up again and again in the micro data – for example, when looking at agricultural fields or manufacturing plants – they were not showing up in the existing macro-level studies, and we wanted to understand why.”
Given global mean temperatures continuing to increase at the current pace, the researchers’ model forecast that by 2100 global economic output of 77 percent of the world’s economies would fall as compared to current levels.
Furthermore, global incomes could drop 23 percent by 2100 as compared to those if global temperatures were not rise, according to the principal scenario analysis. Other scenario analyses forecast much higher declines, as much as two times higher or more. The likelihood of income declines of more than 20 percent of current levels is at least 40 percent, and much higher in some, Stanford News Service’s Laura Seaman reported.
These estimates are substantially larger than existing models indicate, a difference the researchers attributed to their updated and data-driven understanding regarding  how countries have responded historically to temperature increases.
A common assumption among researchers has been that wealth and technology protect rich countries from the economic impacts of climate change, because they use these resources to adapt to higher temperatures. “Under this hypothesis, the impacts of future warming should lessen over time as more countries become richer,” Burke said. “But we find limited evidence that this is the case.”
On the contrary, Burke’s team found that, historically, rich countries did not appear to respond any differently to temperature change than poor countries.
“The data definitely don’t provide strong evidence that rich countries are immune from the effects of hot temperatures,” co-lead author and UCal, Berkeley co-lead author Solomon Hsiang said. “Many rich countries just happen to have cooler average temperatures to start with, meaning that future warming will overall be less harmful than in poorer, hotter countries.”
*Image credits: NOAA
