2011-02-15 09:45:34Papers linking climate to extreme weather
John Cook

john@skepticalscience...
124.186.217.214

This email was in a mailing list discussion I subscribe to so I'm just throwing it here for future reference - I imagine some of these papers will come in useful down the track:

Besides Kevin's below, and Gavin's http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8-5.html#table-3-8

There's this:
http://www.nicholas.duke.edu/news/increasingly-variable-summer-rainfall-in-southeast-linked-to-climate-change

and this
http://www2.ucar.edu/news/1036/record-high-temperatures-far-outpace-record-lows-across-us

Someone also posted these:

Zhang et al. (2007): Detection of human influence on twentieth-century precipitation trends. (Nature) “We show that anthropogenic forcing has had a detectable influence on observed changes in average precipitation within latitudinal bands, and that these changes cannot be explained by internal climate variability or natural forcing. We estimate that anthropogenic forcing contributed significantly to observed increases in precipitation in the Northern Hemisphere mid-latitudes, drying in the Northern Hemisphere subtropics and tropics, and moistening in the Southern Hemisphere subtropics and deep tropics. The observed changes, which are larger than estimated from model simulations, may have already had significant effects on ecosystems, agriculture and human health in regions that are sensitive to changes in precipitation, such as the Sahel.”

Christidis et al. (2011): The role of human activity in the recent warming of extremely warm daytime temperatures. (J. Climate).
“Our analysis is the first that attempts to partition the observed change in warm daytime extremes between its anthropogenic and natural components and hence attribute part of the change to possible causes. Changes in the extreme temperatures are represented by the temporal changes in a parameter of an extreme value distribution. Regional distributions of the trend in the parameter are computed with and without human influence using constraints from the global optimal fingerprinting analysis. Anthropogenic forcings alter the regional distributions, indicating that extremely warm days have become hotter.”

Zwiers et al. (2010): Anthropogenic Influence on Long Return Period Daily Temperature Extremes at Regional Scales. (J. Climate).
“We therefore conclude that the influence of anthropogenic forcing has had a detectable influence on extreme temperatures that have impacts on human society and natural systems at global and regional scales. External influence is estimated to have resulted in large changes in the likelihood of extreme annual maximum and minimum daily temperatures. Globally, waiting times for extreme annual minimum daily minimum and daily maximum temperatures events that were expected to recur once every 20 years in the 1960s are now estimated to exceed 35 and 30 years respectively. . In contrast, waiting times for circa 1960s 20-year extremes of annual maximum daily minimum and daily maximum temperatures are estimated to have decreased to less than 10 and 15 years respectively.”

Krishnamurthy et al. (2009): Changing Frequency and Intensity of Rainfall Extremes over India from 1951 to 2003. (J. Climate).
“Statistically significant increasing trends in extremes of rainfall are identified over many parts of India, consistent with the indications from climate change models and the hypothesis that the hydrological cycle will intensify as the planet warms. Specifically, for the exceedance of the 99th percentile of daily rainfall, all locations where a significant increasing trend in frequency of exceedance is identified also exhibit a significant trend in rainfall intensity.”

Teixeira and Satyamurty (2011): Trends in the Frequency of Intense Precipitation Events in Southern and Southeastern Brazil during 1960–2004. (J. Climate).
“In both regions, annual heavy and extreme rainfall event frequencies present increasing trends in the 45-year period. However, only in Southern Brazil is the trend statistically significant. Although longer time series are necessary to ensure the existence of long term trends, the positive trends are somewhat alarming since they indicate that climate changes, in terms of rainfall regimes, are possibly under way in Brazil.”

Ding et al. (2009): Changes in hot days and heat waves in China during 1961–2007. (Int. J. Clim.) “Over most of China except northwestern China, the frequency of HDs was high during the 1960s–1970s, low in the 1980s, and high afterwards, with strong interannual variations. A remarkable increasing trend of HDs occurred after the 1990s in all regions. ”

Rodda et al.(2009): A comparative study of the magnitude, frequency and distribution of intense rainfall in the United Kingdom. (Int. J. Clim).
“Most noticeably, increases up to 20% have occurred in the north-west of the country and in parts of East Anglia. There have also been changes in other areas, including decreases of the same magnitude over central England. The implications of these changes are considered.”

Kyselý (2009): Recent severe heat waves in central Europe: how to view them in a long-term prospect? (Int. J. Clim).
“Owing to an increase in mean summer temperatures, probabilities of very long heat waves have already risen by an order of magnitude over the recent 25 years, and are likely to increase by another order of magnitude by around 2040 under the summer warming rate assumed by the mid-scenario. Even the lower bound scenario yields a considerable decline of return periods associated with intense heat waves. Nevertheless, the most severe recent heat waves appear to be typical rather of a late 21st century than a mid-21st century climate. ”

Gallant and Karoly (2010): A Combined Climate Extremes Index for the Australian Region (J. Climate) “Over the whole country, the results show an increase in the extent of hot and wet extremes and a decrease in the extent of cold and dry extremes annually and during all seasons from 1911 to 2008 at a rate of between 1% and 2% decade21. These trends mostly stem from changes in tropical regions during summer and spring. There are relationships between the extent of extreme maximum temperatures, precipitation, and soil moisture on interannual and decadal time scales that are similar to the relationships exhibited by variations of the means. However, the trends from 1911 to 2008 and from 1957 to 2008 are not consistent with these relationships, providing evidence that the processes causing the interannual variations and those causing the longer-term trends are different.”

Romps (2011): Response of Tropical Precipitation to Global Warming. (J. Atmos. Sci.) “There are many properties of convection that can change as the atmosphere warms, each of which could produce deviations from CC scaling. These properties include the effective water-vapor gradient, cloud pressure depth, and cloud velocity. A simple theory is developed that predicts the changes in these properties consistent with CC scaling. Convection in the cloud-resolving simulations is found to change as predicted by this theory, leading to an ~20% increase in local precipitation fluxes when the CO2 concentration is doubled. Overall, an increase in CO2 leads to more vigorous convection, composed of clouds that are wider, taller, and faster.”

Wentz et al. (2007): How Much More Rain Will Global Warming Bring? (Science).
“Climate models and satellite observations both indicate that the total amount of water in the atmosphere will increase at a rate of 7% per kelvin of surface warming. However, the climate models predict that global precipitation will increase at a much slower rate of 1 to 3% per kelvin. A recent analysis of satellite observations does not support this prediction of a muted response of precipitation to global warming. Rather, the observations suggest that precipitation and total atmospheric water have increased at about the same rate over the past two decades.”

Allan et al. (2010): Current changes in tropical precipitation. (Environmental research letters).
“Analysing changes in extreme precipitation using daily data within the wet regions, an increase in the frequency of the heaviest 6% of events with warming for the SSM/I observations and model ensemble mean is identified. The SSM/I data indicate an increased frequency of the heaviest events with warming, several times larger than the expected Clausius–Clapeyron scaling and at the upper limit of the substantial range in responses in the model simulations.”

Allan and sodden (2008): Atmospheric Warming and the Amplification of Precipitation Extremes. (Science).
“We used satellite observations and model simulations to examine the response of tropical precipitation events to naturally driven changes in surface temperature and atmospheric moisture content. These observations reveal a distinct link between rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods. Furthermore, the observed amplification of rainfall extremes is found to be larger than that predicted by models, implying that projections of future changes in rainfall extremes in response to anthropogenic global warming may be underestimated.”

Lenderink and Meijgaard (2008) Increase in hourly precipitation extremes beyond expectations from temperature changes. (Nature).
“Indeed, changes in daily precipitation extremes in global climate models seem to be consistent with the 7% increase per degree of warming given by the Clausius–Clapeyron relation3, 4, but it is uncertain how general this scaling behaviour is across timescales. Here, we analyse a 99-year record of hourly precipitation observations from De Bilt, the Netherlands, and find that one-hour precipitation extremes increase twice as fast with rising temperatures as expected from the Clausius–Clapeyron relation when daily mean temperatures exceed 12 °C. In addition, simulations with a high-resolution regional climate model show that one-hour precipitation extremes increase at a rate close to 14% per degree of warming in large parts of Europe. Our results demonstrate that changes in short-duration precipitation extremes may well exceed expectations from the Clausius–Clapeyron relation. “

2011-02-15 09:50:00Follow-up email, more gold nuggets
John Cook

john@skepticalscience...
124.186.217.214
First paper by Zhang et al:
This is an attribution study of changes in extremes of precipitation using and anthropogenic (total forcing= ANT) runs vs a natural (NAT) runs.
The problem is that the models do not do precipitation well.  The period analyzed is 1951 to 1999.  Well, in the 1990s there were two major things that happened in nature that are really important.  One is the 1997/98 El Nino that was exceptional and contributed to major changes in precipitation and extremes in 1997 and 1998.   None of the CMIP3 models, of course, have that.  It is not discussed.  The other is Mt Pinatubo in the early 1990s that affected precip in major ways, see:
Trenberth, K. E., and A. Dai, 2007: Effects of Mount Pinatubo volcanic eruption on the hydrological cycle as an analog of geoengineering. Geophys. Res. Lttrs., 34, L15702, doi:10.1029/2007GL030524. [PDF]
for 2 years.
This presumably comes under "natural forcings" but it is not well simulated by most models.  But it is interesting that the "all-NAT" differences in the Supplemental Fig 3 are quite similar to the anomalies in our paper associated with Pinatubo.  So the stuff they struggle with on NAT vs ANT is probably linked to Pinatubo effects.

So it is disappointing that this paper does not discuss things like the major ENSO, or Pinatubo on their results (except insofar as NAT includes Pinatubo).   They also don't discuss trends in mean precipitation along with the extremes.  The models don't simulate the changes in the mean well: for instance the substantial increases in precip for the US.  This relates to regional climate change and things like PDO and El Nino.  So in the absence of the ability to simulate the mean, why should the extremes be simulated?   The answer is that it is related to the increases in moisture that is associated with warming and higher SSTs: in other words it is largely a thermodynamic effect.  In that respect the paper is useful and relevant to what has happened in last year or two.

Both papers are very much statistical in nature and deal with attribution.  In the second paper, the model performance wrt precipitation is not commented on, but it is not great.  So they are using inadequate tools to do this well. The result is probably quite conservative.
2011-02-15 09:51:59And then this intriguing teaser (good blog fodder, indeed)
John Cook

john@skepticalscience...
124.186.217.214
FYI, there are two papers coming out in Nature this week on the anthropogenic contribution to extreme events.  Should be some good blog fodder.
2011-02-15 14:36:01
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Looking forward to seeing those Nature papers John.