Modern Warming – Climate Variability or Climate Change?

By Renee Hannon – Re-Blogged From


In the mid-1900’s many scientists were suggesting the Earth was cooling. Now scientists are forecasting global warming. Indeed, instrumental data shows global temperatures warmed by approximately 1-degree C during the past 165+ years. With warming rates of 0.5 to over 1.3 degrees C per century this has caused considerable alarm for many. This recent warming is commonly attributed to increasing greenhouse gases, primarily CO2.

This post examines natural paleoclimate trends and simple characteristics of past and present climate cycles at different time scales. Data suggests distinct differences between short-term climate variability and longer-term climate change. This is important because short-term climate variability can be misinterpreted as underlying climate change resulting in poor science and potentially worse policy decisions. This post compares modern instrumental trends to paleoclimate trends. This comparison reveals modern warming has characteristics of natural short-term climate variability and not long-term climate change.

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Weekly Climate and Energy News Roundup #254

By Ken Haapala, President, Science and Environmental Policy Project

What Happens Now? Roy Spencer reported that the early calculations for atmospheric global temperature report from the Earth System Science Center at the University of Alabama in Huntsville (UAH) show that 2016 was slightly warmer than the prior hot year of 1998 by a statically insignificant 0.02ºC. The earlier part of the year was warmer, but temperatures dropped in the latter part of the year. Spencer produces a table ranking the 38 years by the anomaly from the average: 2016 is now 1, 1998 is 2, 2010 is 3, 2015 is 4 and 2002 is 5. The top 2 years are about 0. 5ºC from the anomaly, and the departure from the anomaly lessens significantly after that. According to Paul Homewood, the UAH calculations were independently confirmed by data from Remote Sensing Systems (RSS).

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Weekly Climate and Energy News Roundup #179

The Week That Was: May 9, 2015 Brought to You by

By Ken Haapala, President, Science and Environmental Policy Project

Controversial Points: On her web site, Climate Etc., Judith Curry explores what she considers the most controversial points in climate science. The points must be agreed upon in order to resolve the controversies. To her, the two general issues are: 1) whether the warming since 1950 has been dominated by human causes and 2) how much the planet will warm in the 21st century?

From these general issues she develops the specific technical issues that need to be resolved, including:

  • “Causes of the 1900-1940 warming; the cooling from 1940-1976; and the recent hiatus in warming since 1998.  How are these explained in context of AGW being the dominant influence since 1950?
  • Solar impacts on climate (including indirect effects).  What are the magnitudes and nature of the range of physical mechanisms?
  • Nature and mechanisms of multi-decadal and century scale natural internal variability.  How do these modes of internal variability interact with external forcing, and to what extent are these modes separable from externally forced climate change?
  • Deep ocean heat content variations and mechanisms of vertical heat transfer between the surface and deep-ocean.
  • Sensitivity of the climate system to external forcing, including fast thermodynamic feedbacks (water vapor, clouds, lapse rate).
  • Climate dynamics of clouds: Could changes in cloud distribution or optical properties contribute to the global surface temperature hiatus? How do cloud patterns (and TOA and surface radiative fluxes) change with shifts in atmospheric circulation and teleconnection regimes (e.g. AO, NAO, PDO)? How do feedbacks between clouds, surface temperature, and atmospheric thermodynamics/circulations interact with global warming and the atmospheric circulation and teleconnection regimes?”

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