You may have been hearing about the contretemps regarding emails to and from the Climatic Research Unit (CRU) of the University of East Anglia. I have no particular desire now, frankly, to get into all the allegations, counter-allegations, etc., etc. that have been flying around in the news, the blogosphere and beyond. There is a discussion – more like a ping pong match – on this under one of my posts here if you want to see my perspective and some others. I will, however, quote for you what I have quoted before, from a recent editorial in the “FT”. Here’s what I think is the heart of the matter: “The most important point to make about the leaked correspondence is that it does not undermine the scientific case for cutting emissions of carbon dioxide to fight climate change, which is growing more rather than less compelling. None of the e-mails seized on by sceptics shows manipulation of the science itself.”
With that in mind, let’s step back and take a look at the science. There is no more lucid and succinct explanation of the science and practice of collecting and analyzing global temperature records than this from Dr. Peter Stott at the UK’s Met Office. He explains that there are three centers, working independently and using different methods, that gather and calculate the temperature data: the Met Office, in collaboration with the CRU, NASA’s Goddard Institute for Space Studies (GISS), and the National Climatic Data Center (NCDC), which is part of the National Oceanic and Atmospheric Administration (NOAA). These centers receive tens of thousands of temperature observations that are taken across the globe, on land and at sea, every day. Considerable care is taken in the quality assurance for these observations.
Stott explains how the data are reported. “Absolute temperatures are not used directly to calculate the global-average temperature. They are first converted into ‘anomalies’, which are the difference in temperature from the ‘normal’ level. The normal level is calculated for each observation location by taking the long-term average for that area over a base period. For HadCRUT3, this is 1961-1990.” (HadCRUT3 is the record produced by the Met Office and CRU.)
The UN’s Intergovernmental Panel on Climate Change (IPCC) has used this data, among others, to produce its conclusions on global temperature. (The IPCC shared the Nobel Peace Prize with Al Gore in 2007, as you may remember.) Here is a graph from the Fourth Assessment Report of the IPCC in 2007.
Figure SPM.4. Comparison of observed continental- and global-scale changes in surface temperature with results simulated by climate models using either natural or both natural and anthropogenic forcings. Decadal averages of observations are shown for the period 1906-2005 (black line) plotted against the centre of the decade and relative to the corresponding average for the period 1901-1950. Lines are dashed where spatial coverage is less than 50%. Blue shaded bands show the 5 to 95% range for 19 simulations from five climate models using only the natural forcings due to solar activity and volcanoes. Red shaded bands show the 5 to 95% range for 58 simulations from 14 climate models using both natural and anthropogenic forcings.
It shows the temperature anomaly of increasingly rapid warming which correlates with how the models predict the warming should proceed. As Stott puts it: “The warming has been particularly rapid since the 1970s. The records also clearly show each decade since the 1970s has been successively warmer than the last, including the decade since 2000.”
Now here is a graph that I use in my MS in Global Affairs class at NYU. It portrays not only the rise in temperatures (since 1970), but it correlates these to tens of thousands of observations of physical and biological changes that are “consistent with warming.”
Figure SPM.2. Locations of significant changes in data series of physical systems (snow, ice and frozen ground; hydrology; and coastal processes) and biological systems (terrestrial, marine and freshwater biological systems), are shown together with surface air temperature changes over the period 1970-2004. A subset of about 29,000 data series was selected from about 80,000 data series from 577 studies. These met the following criteria: (1) ending in 1990 or later; (2) spanning a period of at least 20 years; and (3) showing a significant change in either direction, as assessed in individual studies. These data series are from about 75 studies (of which about 70 are new since the TAR) and contain about 29,000 data series, of which about 28,000 are from European studies. White areas do not contain sufficient observational climate data to estimate a temperature trend. The 2 × 2 boxes show the total number of data series with significant changes (top row) and the percentage of those consistent with warming (bottom row) for (i) continental regions: North America (NAM), Latin America (LA), Europe (EUR), Africa (AFR), Asia (AS), Australia and New Zealand (ANZ), and Polar Regions (PR) and (ii) global-scale: Terrestrial (TER), Marine and Freshwater (MFW), and Global (GLO). The numbers of studies from the seven regional boxes (NAM, EUR, AFR, AS, ANZ, PR) do not add up to the global (GLO) totals because numbers from regions except Polar do not include the numbers related to Marine and Freshwater (MFW) systems. Locations of large area marine changes are not shown on the map.
Is there rapid warming? Yes. Is it impacting our home? You bet. Should we care? How can we not?
