Take the climate change quiz. How warm was August? What’s the trend?
Summary: Most of you have read scores, or hundreds of articles about global warming. Drawing on what you learned from those, estimate how much warmer was the world in August than the 30-year average? For bonus credit, what was the Earth’s rate of warming per year (or per decade) since 1979 (when satellites began taking accurate global measurements. It’s hidden history. Without knowing that, talking about public policy action — or inaction — seems inappropriate.
- Status report: what do satellites tell us about global warming?
- The UK Met Office shows the long-term history of warming
- Who produces this data & analysis?
- About The Elusive Absolute Surface Air Temperature (SAT)
- A few key things to remember about global warming!
- For More Information
To the right is a typical over-the-top image to arouse fear, about a world now less than one °F warmer than the 30-year average.
(1) Status report: what do satellites tell us about global warming in July 2013?
The August 2013 Global Temperature Report
by the Earth System Science Center of the University of Alabama in Huntsville (blue is cold; red warm}
Key points from the report, which show a world that has warmed since 1979, but only slightly (few alarmists know this; fewer admit it):
- Global composite temperature in July: +0.16°C (0.29°F) above the average for August during 1981-2010.
- Global climate trend of temperature starting in 16 November 1978: +0.14°C (0.3°F) per decade.
- Compared to seasonal norms, in August the coolest area on the globe was southern Greenland, where temperatures in the troposphere were about 1.97°C (3.55°F) cooler than normal,
- The warmest area was south of New Zealand in the South Pacific, where tropospheric temperatures were 2.82°C (about 5.1°F) warmer than seasonal norms.
- Anomalies are computed vs a 30 year base period. The World Meteorological Organization (WMO) recommends using the latest decade for the 30-year average.
Let’s look at the data since 1979 (the satellite dataset). The following graph shows, very roughly, 2 decades of cool weather, then 15 years of warm:
Roy Spencer (principal scientists on the team) shows another perspective on this data (at his website). Wide swings in temperature; relatively flat trend since 1998. For more about the pause see summaries of the growing body research about it here, and the IPCC’s view here.
(2) The UK Met Office shows the long-term history — the vital context
These numbers cannot be properly understood until put in a historical context, from page 10 of “The Recent Pause in Global Warming” published by the UK Met Office in July. Anthropogenic factors became the largest (not the only) driver since roughly 1950.
(3) Who produces this data and analysis?
About the global satellite data
As part of an ongoing joint project between The University of Alabama in Huntsville, NOAA and NASA, John Christy (professor of atmospheric science and director of the Earth System Science Center (ESSC) at U AL-Huntsville) and Dr. Roy Spencer (an ESSC principal scientist) use data gathered by advanced microwave sounding units on NOAA and NASA satellites to get accurate temperature readings for almost all regions of the Earth. This includes remote desert, ocean and rain forest areas where reliable climate data are not otherwise available.
The satellite-based instruments measure the temperature of the atmosphere from the surface up to an altitude of about 8,000 above sea level.
Neither Christy nor Spencer receives any research support or funding from oil, coal or industrial companies or organizations, or from any private or special interest groups. All of their climate research funding comes from federal and state grants or contracts.
(4) Some of the key things to remember about global warming!
While cheering for their faction of scientists, laypeople often lose sight of the big picture — the key elements for making public policy about this important issue.
- The work of the IPCC and the major science institutes are the best guides for information about these issues.
- The major global temperature measurement systems tell — broadly speaking — the same story since the 1970s: two decades of cooling, two of warming, followed by a pause (see summaries of the growing body research about it here, and the IPCC’s view here).
- This is consistent with the larger firm conclusions of climate scientists: two centuries of warming, coming in pulses (ie, waves), with anthropogenic factors becoming the largest (not the only) driver since roughly 1950.
- There is a debate about the attribution (causes) of past warming — which probably varied over time — between natural drivers (eg, rebound from the Little Ice Age, solar influences) and anthropogenic drivers (eg, CO2, aerosols, land use changes). Other that that stated in #3, the IPCC’s reports make few claims about attribution of climate activity, as this remains actively debated in the literature.
- There is an even larger debate about climate forecasts, both the extent of future CO2 emissions and the net effects of the various natural and anthropogenic drivers.
For the past five years my recommendations have been the same:
- More funding for climate sciences. Many key aspects (eg, global temperature data collection and analysis) are grossly underfunded.
- Wider involvement of relevant experts in this debate. For example, geologists, statisticians and software engineers have been largely excluded — although their fields of knowledge are deeply involved.
(5) About The Elusive Absolute Surface Air Temperature (SAT)
Q. What exactly do we mean by Surface Air Temperature?
A. I doubt that there is a general agreement how to answer this question. Even at the same location, the temperature near the ground may be very different from the temperature 5 ft above the ground and different again from 10 ft or 50 ft above the ground. Particularly in the presence of vegetation (say in a rain forest), the temperature above the vegetation may be very different from the temperature below the top of the vegetation. A reasonable suggestion might be to use the average temperature of the first 50 ft of air either above ground or above the top of the vegetation. To measure SAT we have to agree on what it is and, as far as I know, no such standard has been suggested or generally adopted. Even if the 50 ft standard were adopted, I cannot imagine that a weather station would build a 50 ft stack of thermometers to be able to find the true SAT at its location.
Q. What do we mean by daily mean SAT ?
A. Again, there is no universally accepted correct answer. Should we note the temperature every 6 hours and report the mean, should we do it every 2 hours, hourly, have a machine record it every second, or simply take the average of the highest and lowest temperature of the day ? On some days the various methods may lead to drastically different results.
Read the rest here.
(6) For More Information
(a) Reference Pages about climate on the FM sites:
(b) Other posts in this series about global warming:
- Still good news: global temperatures remain stable, at least for now., 14 October 2012 — Scientists analysis of the pause
- When did we start global warming? See the surprising answer., 18 October 2012
- The IPCC sees the pause in global warming!, 18 December 2012
- Lessons about global warming from Alaska, 9 January 2013
- Secrets about global warming that you must not know, least they ruin the narrative, 22 January 2013
- Hidden news about our weather in July: experts tell us what even well-informed people do not know., 8 August 2013
- One of the most important questions we face: when will the pause in global warming end?, 25 August 2013