Arguments
Software
Resources
Comments
The Consensus Project
Translations
About
Support
Latest Posts
- 2024 SkS Weekly Climate Change & Global Warming News Roundup #47
- Fact brief - Has human-caused climate change increased extreme weather?
- Skeptical Science New Research for Week #47 2024
- Durability of carbon dioxide removal is critical for stabilizing temperatures
- Sabin 33 #3 - Solar panels generate too much waste and will overwhelm landfills
- Here’s how governments could fix their Paris climate commitment failures
- 2024 SkS Weekly Climate Change & Global Warming News Roundup #46
- Skeptical Science New Research for Week #46 2024
- 20 fact briefs published in collaboration with Gigafact!
- Sabin 33 #2 - Are toxic heavy metals from solar panels posing a threat to human health?
- 2024 will be the first year above 1.5°C
- 2024 SkS Weekly Climate Change & Global Warming News Roundup #45
- Fact brief - Is there an expert consensus on human-caused global warming?
- Skeptical Science New Research for Week #45 2024
- The planet is ‘on the brink of an irreversible climate disaster,’ scientists warn
- Sabin 33 #1 - Are electromagnetic fields from solar farms harmful to human health?
- Volunteer activity: Evaluate automated climate misinformation debunkings
- 2024 SkS Weekly Climate Change & Global Warming News Roundup #44
- Fact brief - Are most glaciers growing?
- Rebutting 33 False Claims About Solar, Wind, and Electric Vehicles thanks to the Sabin Center for Climate Change Law
- Skeptical Science New Research for Week #44 2024
- The hidden health toll of hurricanes
- Climate Adam: Is climate change fuelling mega hurricanes?
- Jobs in wind, solar, and energy storage are booming. Is your state keeping up?
- 2024 SkS Weekly Climate Change & Global Warming News Roundup #43
- Fact brief - Do volcanoes emit more CO2 than humans?
- Skeptical Science New Research for Week #43 2024
- Why widening highways doesn’t reduce traffic congestion
- Climate Risk
- Welcome to the world of personal air conditioning
Archived Rebuttal
This is the archived Intermediate rebuttal to the climate myth "Global warming stopped in 1998, 1995, 2002, 2007, 2010, ????". Click here to view the latest rebuttal.
What the science says...
| 2007's dramatic cooling is driven by strong La Niña conditions which historically has caused similar drops in global temperature. It is also exacerbated by unusually low solar activity. |
The flaw in this interpretation is in drawing conclusions about long term climate change over a relatively short period of 13 months. Particularly when a large portion of that cooling occured over one month (January 2008). Only over a period of years to decades can you confidently discern climate trends. Otherwise, you run the danger of mistaking weather for climate.
Nevertheless, several important questions remain - what's causing this sudden cooling and is it the start of a long term trend?
Is the sun driving global cooling?
The general consensus among skeptic blogs is that diminished solar activity is the cause. The sun is currently at solar minimum - cycle 23 just ended and cycle 24 is having trouble kicking along. It's as cool as it gets in the solar cycle.
However, a temperature drop of 0.6°C would require a dramatic reduction in Total Solar Irradiance (TSI). According to theoretical calculations at Atmoz, TSI would need to fall to 1347.65 W/m2 to produce a global cooling of 0.6°C. In other words, 13 W/m2 less than current levels. This is ludicrously large considering the solar cycle varies only around 1.3 W/m2.
Alternatively, Camp 2007 adopts an empirical approach to calculate solar influence on global temperature. He determines the solar cycle contributes 0.18°C cooling to global temperatures as the sun moves from maximum to minimum. Employing back of a napkin calculations, TSI would need to fall roughly 4.3 W/m2 to provide 0.6°C of cooling.
Either way, TSI needs to drop considerably to be considered the driver of 2007 cooling. So what has the sun been doing over the last few years?
Figure 2: TSI Composite and Sunspot Numbers (graph courtesy Greg Kopp).
Satellite measurements show no dramatic drop in TSI over the past several years. Instead, the solar cycle is following its usual 11 year cycle, flattening out as it reaches solar minimum. So if not the sun, what's causing the cooling?
La Niña - the likely culprit
Currently, the Pacific Ocean is in a La Niña phase. During La Niña, cold waters upwell to cool large areas of the equatorial Pacific Ocean. This has the effect of cooling the atmosphere. During the La Niña episode of 1999, global temperatures dropped around 0.5°C.
The Southern Oscillation Index (SOI) is a measure of La Niña. Positive SOI corresponds to a La Niña phase. In 2006, the Pacific Ocean was in El Niño phase (negative SOI). However, in late 2006, El Niño subsided and in mid 2007, crossed into La Niña phase. La Niña peaked around January 2008 and is the strongest La Niña since 1999. In the Eastern Pacific, sea-surface temperatures are about two degrees colder than normal over an area the size of the United States.
Figure 3: Southern Oscillation Index (graph courtesy bom.giv.au).
Signal vs. Noise
Ultimately arguments that global warming has magically stopped are based on a failure to differentiate between short-term noise and long-term global warming signal.
Figure 4: BEST land-only surface temperature data (green) with linear trends applied to the timeframes 1973 to 1980, 1980 to 1988, 1988 to 1995, 1995 to 2001, 1998 to 2005, 2002 to 2010 (blue), and 1973 to 2010 (red).
Updated on 2011-11-03 by John Cook.
THE ESCALATOR
(free to republish)