Rate of global temperature change for historical observations with the influence of 10 volcanoes, solar irradiance changes, and ENSO removed (Rahmstorf et al 2012). Each of the lines extending from 1998 through 2012 represents a different historical dataset from Rahmstorf et al. For dataset key see Rahmstorf et al (2012). The central, high, and low estimates from the GCAM RCP4.5 scenario over 20-year periods are also shown as thick black lines. Also shown, as an “X”, is the average rate of change over 1987-2010 from models in the CMIP5 archive from Cohen, et al. (2012). Graphic: Smith, et al., 2015

By James Sullivan 
10 March 2015

(Science Recorder) – According to a new paper published Monday in Nature Climate Change, it’s about to get a whole lot hotter – that’s the projected trend after looking at the weather over 40-year periods. While the fact that next century may bring us temperatures over the two degree Celsius mark (that’s 33.5 degrees Fahrenheit) sounds alarming enough, imagine a milennium of record temperatures, that could bring about the detriment of human survival.

According to the latest research, the Arctic, along with North America and Europe will be among the first regions on Earth whose climates will significantly reshape – with wet areas becoming much wetter and dry areas desiccating further. Therefore, it is imperative that policy makers and researchers begin planning for adaptations to this new environment.

“Essentially the world is entering a new regime where what is normal is going to continue to change and it’s changing at a rate than natural processes might not be able to keep up with,” said Steven Smith, a researcher at the Pacific Northwest National Laboratory.

Although an analysis of the past millennium shows a fluctuation of temperatures at 0.2°F each decade – both moving up and down, the last four decades show something rather alarming. Not only have temperatures climbed consistently each decade since 1975, the warming is encroaching on an average of 0.4°F per decade. It’s a rate that’s only barely within historical trends. By 2020, researchers expect these warming rates to accelerate beyond the historical bounds of the last 1,000 years — continuing to rise. If nations do not work to control greenhouse gas emissions, this rate is expected to spike up to 0.7°F per decade, a high that is expected to remain until at least 2100.

These historic levels of warming are expected to begin in the northern hemisphere, which is already seeing a significant decrease in ice levels. Temperatures in the Arctic are expected to rise 1.1°F per decade by the year 2040, while the warming rates in North America and Europe will be somewhat lower, the rates of warming will be equally unprecedented.

“With those high rates of change, there’s not going to be anything close to equilibrium,” said Smith. [more]

Global warming records unseen for 1,000 years could become the norm


ABSTRACT: Anthropogenically driven climate changes, which are expected to impact human and natural systems, are often expressed in terms of global-mean temperature1. The rate of climate change over multi-decadal scales is also important, with faster rates of change resulting in less time for human and natural systems to adapt2. We find that present trends in greenhouse-gas and aerosol emissions are now moving the Earth system into a regime in terms of multi-decadal rates of change that are unprecedented for at least the past 1,000 years. The rate of global-mean temperature increase in the CMIP5 (ref. 3) archive over 40-year periods increases to 0.25 ± 0.05 °C (1σ) per decade by 2020, an average greater than peak rates of change during the previous one to two millennia. Regional rates of change in Europe, North America and the Arctic are higher than the global average. Research on the impacts of such near-term rates of change is urgently needed.

Near-term acceleration in the rate of temperature change

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