The period creating Hansen’s 1988 warming alarm, given as evidence to Congress, ran for 10 years, being 1977-87.

The “second half of the 20th century” warming found by the IPCC to have been “very likely anthropogenic” was confined to 20 years, being 1979-98.

Now, there has been no statistically significant warming for 15 years, being 1996-2011.

NOAA say, however, that 0.03°C/decade warming is the most likely measure for 1996-2011 (although the signal is lost in noise during such a short period).

The signal in the past decade, being 2002-12, is also overcome by noise, but the most likely measure is cooling of 0.02/decade.

What would an objective analyst make of all these patterns? I suspect a purist would say we just don’t know what has happened during the past 15 years, but a plateau seems to be the best estimate. So, in the most recent half-century we had three different more-or-less equal movements – down, then up, then sideways.

How does one answer people who ask – “do you sceptics at least agree that the world is warming?”

* Justin Sheffield,
* Eric F. Wood
* & Michael L. Roderick

Nature, Published online 14 November 2012

Drought is expected to increase in frequency and severity in the future as a result of climate change, mainly as a consequence of decreases in regional precipitation but also because of increasing evaporation driven by global warming1, 2, 3. Previous assessments of historic changes in drought over the late twentieth and early twenty-first centuries indicate that this may already be happening globally. In particular, calculations of the Palmer Drought Severity Index (PDSI) show a decrease in moisture globally since the 1970s with a commensurate increase in the area in drought that is attributed, in part, to global warming4, 5. The simplicity of the PDSI, which is calculated from a simple water-balance model forced by monthly precipitation and temperature data, makes it an attractive tool in large-scale drought assessments, but may give biased results in the context of climate change6. Here we show that the previously reported increase in global drought is overestimated because the PDSI uses a simplified model of potential evaporation7 that responds only to changes in temperature and thus responds incorrectly to global warming in recent decades. More realistic calculations, based on the underlying physical principles8 that take into account changes in available energy, humidity and wind speed, suggest that there has been little change in drought over the past 60 years. The results have implications for how we interpret the impact of global warming on the hydrological cycle and its extremes, and may help to explain why palaeoclimate drought reconstructions based on tree-ring data diverge from the PDSI-based drought record in recent years9, 10.

http://www.nature.com/nature/journal/v491/n7424/full/nature11575.html

A new paper published in Environmental Research Letters examines satellite data over Eurasia to find that total cloud cover acts as a net negative feedback to cool the climate.

Qiuhong Tang and Guoyong Leng 2012 Environ. Res. Lett. 7 014004 doi:10.1088/1748-9326/7/1/014004

Damped summer warming accompanied with cloud cover increase over Eurasia from 1982 to 2009

Abstract
The relationship between summer temperature, total cloud cover and precipitation over Eurasia was investigated using observation-based products of temperature and precipitation, and satellite-derived cloud cover and radiation products. We used a partial least squares regression approach to separate the local influences of cloud cover and precipitation on temperature variations. Our results suggest that the variance of summer temperature is partly explained by changes in summer cloudiness. The summer temperature dependence on cloud cover is strong at the high latitudes and in the middle latitude semi-humid area, while the dependence on precipitation is strong in the Central Asia arid area and the southern Asia humid area. During the period 1982–2009, the damped warming in extended West Siberia was accompanied with increases in cloud cover, and the pronounced warming in Europe and Mongolia was associated with a decrease in cloud cover and precipitation. Our results suggest that cloud cover may be the important local factor influencing the summer temperature variation in Eurasia while precipitation plays an important role at the middle latitudes.

http://hockeyschtick.blogspot.co.nz/2012/11/new-paper-finds-clouds-cool-climate.html

Skeptical Science: What is the net feedback from clouds?

What the science says…

Evidence is building that net cloud feedback is likely positive and unlikely to be strongly negative.

http://www.skepticalscience.com/clouds-negative-feedback.htm

I’ll keep an eye out for Tang and Leng 2012 in Ari Jokimäki’s next ‘New research from last week’ post at SkS.