Not exact matches
Attributable human - induced
changes in the likelihood and magnitude of the
observed extreme
precipitation during Hurricane Harvey.
To see how increased temperatures might contribute to the reductions in the river's flow that have been
observed since 2000, Udall and Overpeck reviewed and synthesized 25 years of research about how climate and climate
change have and will affect the region and how temperature and
precipitation affect the river's flows.
The
changes shown in these maps compare an average of the model projections to the average temperature and
precipitation benchmarks
observed from 1971 - 2000.
However, the simulations indicate that the sea - ice driven
precipitation changes resemble the global rainfall patterns
observed during that drought, leaving the possibility that Arctic sea - ice loss could have played a role in the recent drought.
«
Observing rainfall in an El Niño year is especially interesting because the prevailing
precipitation patterns
change, often in extreme ways.
The westerlies in the Northern Hemisphere, which increased from the 1960s to the 1990s but which have since returned to about normal as part of NAO and NAM
changes, alter the flow from oceans to continents and are a major cause of the
observed changes in winter storm tracks and related patterns of
precipitation and temperature anomalies, especially over Europe.
This is addressed by evaluating
change in global or large - scale patterns in the frequency or intensity of extremes (e.g.,
observed widespread intensification of
precipitation extremes attributed to human influence, increase in frequency and intensity of hot extremes) and by event attribution methods.
In part because of large intrinsic variability, no evidence was found for
changes in extreme
precipitation attributable to climate
change in the available
observed record.»
These results are based on a comparison of
observed and multi-model simulated
changes in extreme
precipitation over the latter half of the twentieth century analyzed with an optimal fingerprinting technique.
Changes in extreme precipitation projected by models, and thus the impacts of future changes in extreme precipitation, may be underestimated because models seem to underestimate the observed increase in heavy precipitation with w
Changes in extreme
precipitation projected by models, and thus the impacts of future
changes in extreme precipitation, may be underestimated because models seem to underestimate the observed increase in heavy precipitation with w
changes in extreme
precipitation, may be underestimated because models seem to underestimate the
observed increase in heavy
precipitation with warming.
Visible
changes in hydrological cycle have been
observed in the form of
changing precipitation patterns, cropping patterns, droughts, water availability periods, frequency and intensity of heatwaves,
precipitation events and weather - induced natural disasters.
Joseph Bast, who works with the group, highlighted some of the group's conclusions in Forbes: There is little risk of global food insecurity owing to higher levels of CO2, as higher CO2 will greatly aid plant productivity; «No
changes in
precipitation patterns, snow, monsoons, or river flows that might be considered harmful to human well - being or plants or wildlife have been
observed that could be attributed to rising CO2»; and little risk to aquatic or dry - land ecosystems.
Before we accept AGW there is a lot more work to be done to exclude natural variability as the explanation for the
observed changes in temperature and
precipitation.
Osborne, J. M., Lambert, H. Groenendijk, M., Harper, A.B., Koven, C.D., Poulter, B., Pugh, T.A.M., Sitch, S., Stocker, B.D., Wiltshire, A. and Zaehle, S. 2015: Reconciling
precipitation with runoff:
observed hydrological
change in the midlatitudes.
For the entire Northern Hemisphere, there is evidence of an increase in both storm frequency and intensity during the cold season since 1950,1 with storm tracks having shifted slightly towards the poles.2, 3 Extremely heavy snowstorms increased in number during the last century in northern and eastern parts of the United States, but have been less frequent since 2000.11,15 Total seasonal snowfall has generally decreased in southern and some western areas, 16 increased in the northern Great Plains and Great Lakes region, 16,17 and not
changed in other areas, such as the Sierra Nevada, although snow is melting earlier in the year and more
precipitation is falling as rain versus snow.18 Very snowy winters have generally been decreasing in frequency in most regions over the last 10 to 20 years, although the Northeast has been seeing a normal number of such winters.19 Heavier - than - normal snowfalls recently
observed in the Midwest and Northeast U.S. in some years, with little snow in other years, are consistent with indications of increased blocking (a large scale pressure pattern with little or no movement) of the wintertime circulation of the Northern Hemisphere.5 However, conclusions about trends in blocking have been found to depend on the method of analysis, 6 so the assessment and attribution of trends in blocking remains an active research area.
The
observed global greening has occurred in spite of all the many real and imagined assaults on Earth's vegetation that have occurred over the past several decades, including wildfires, disease, pest outbreaks, deforestation, and climatic
changes in temperature and
precipitation, more than compensating for any of the negative effects these phenomena may have had on the global biosphere.
Although there is as yet no convincing evidence in the
observed record of
changes in tropical cyclone behaviour, a synthesis of the recent model results indicates that, for the future warmer climate, tropical cyclones will show increased peak wind speed and increased mean and peak
precipitation intensities.
The increasing atmospheric temperature
observed at elevations of 5,000 m and more can not melt ice directly, but
change the nature of
precipitation.
[2] Bhend J, Whetton P (2013) Consistency of simulated and
observed regional
changes in temperature, sea level pressure and
precipitation.
When I found that
changes in
observed precipitation were largest in autumn, and did not find the same patterns of
precipitation in climate models outputs, I really became skeptical about the use of climate models.
We conclude by underlining that the
observed variation of glacier surface and SLA
changes could be explained by the increase of temperature and decrease of
precipitation in recent years.
Hoerling: «We can also say with high confidence that no appreciable trend toward either wetter or drier conditions has been
observed for statewide average
precipitation since 1895» — «At present, the scientific evidence does not support an argument that the drought there is appreciably linked to human - induced climate
change... In short, the drought gripping California has been
observed before.
Observed changes in short term
precipitation intensity from previous research and the anticipated
changes in flood frequency and magnitude expected due to enhanced greenhouse forcing are not generally evident at this time over large portions of the United States for several different measures of flood flows.
Ozone depletion in the late twentieth century was the primary driver of the
observed poleward shift of the jet during summer, which has been linked to
changes in tropospheric and surface temperatures, clouds and cloud radiative effects, and
precipitation at both middle and low latitudes.
With wNA forest loss, there are significant declines in both
precipitation and temperature during the early growing season, however it is the
change in the relative humidity that dominates the
observed increase in VPD.
I conclude that the
observed global aridity
changes up to 2010 are consistent with model predictions, which suggest severe and widespread droughts in the next 30 — 90 years over many land areas resulting from either decreased
precipitation and / or increased evaporation.
Average
precipitation is
changing in many regions with both increases and decreases and there is a general tendency for increases in extreme
precipitation observed over land areas.
The impacts of climate
change on freshwater systems and their management are mainly due to the
observed and projected increases in temperature, sea level and
precipitation variability (very high confidence).
The widespread trend of increasing heavy downpours is expected to continue, with
precipitation becoming less frequent but more intense.13, 14,15,16 The patterns of the projected
changes of
precipitation do not contain the spatial details that characterize
observed precipitation, especially in mountainous terrain, because the projections are averages from multiple models and because the effective resolution of global climate models is roughly 100 - 200 miles.
Rigorous analyses have shown that natural variability alone can not explain the
observed long - term trends of
changing extremes in temperature and
precipitation.12
Changing distributions of temperature,
precipitation, and carbon dioxide could affect the potency of plant allergens, 43 and there has been an
observed increase of 13 to 27 days in the ragweed pollen season at latitudes above 44 ° N. 43
CAS = Commission for Atmospheric Sciences CMDP = Climate Metrics and Diagnostic Panel CMIP = Coupled Model Intercomparison Project DAOS = Working Group on Data Assimilation and
Observing Systems GASS = Global Atmospheric System Studies panel GEWEX = Global Energy and Water Cycle Experiment GLASS = Global Land - Atmosphere System Studies panel GOV = Global Ocean Data Assimilation Experiment (GODAE) Ocean View JWGFVR = Joint Working Group on Forecast Verification Research MJO - TF = Madden - Julian Oscillation Task Force PDEF = Working Group on Predictability, Dynamics and Ensemble Forecasting PPP = Polar Prediction Project QPF = Quantitative
precipitation forecast S2S = Subseasonal to Seasonal Prediction Project SPARC = Stratospheric Processes and their Role in Climate TC = Tropical cyclone WCRP = World Climate Research Programme WCRP Grand Science Challenges • Climate Extremes • Clouds, Circulation and Climate Sensitivity • Melting Ice and Global Consequences • Regional Sea - Ice
Change and Coastal Impacts • Water Availability WCRP JSC = Joint Scientific Committee WGCM = Working Group on Coupled Modelling WGSIP = Working Group on Subseasonal to Interdecadal Prediction WWRP = World Weather Research Programme YOPP = Year of Polar Prediction
Other factors for the
observed 7 percent increase in runoff from 1936 to 1999 could be
changes in ice and permafrost melt or
changes in the seasonality of
precipitation and runoff, he said.
They looked at the
observed behavior within latitude bands in which the modeled
precipitation changes were more or less of the same character.
Obviously, climate models whose hindcasts differ in sign from what is
observed (Zhang et al., 2007), or which indicate that human influences are indistinguishable from natural
changes (Sarojini et al., 2012) possess no skill in identifying a human - induced climate signal on
observed precipitation across the U.S. and therefore should not be used to make future projections.
We are beginning to sound like a broken record here, but again, it is impossible to present reliable future projections for
precipitations changes across the U.S. (seasonal or annual) from a collection of climate models which largely can not even get the sign (much less the magnitude) of the
observed changes correct.
The first paper cited notes (caveating that observational uncertainties are considerable) that models do not match
observed changes in subtropical relative humidity or in global
precipitation.
Changes in some types of extreme events have already been
observed, for example, increases in the frequency and intensity of heat waves and heavy
precipitation events (see FAQ 3.3).
KEY WORDS:
Observed climatic extremes · Derived indicators · Temperature ·
Precipitation · Climate monitoring · Global
change
GAO representatives visited 15 military installations, and at 12 of them found officials who said they had
observed not only rising temperatures, stronger and more frequent storms, and
changing precipitation patterns, but had also seen how those
changes created «potential impacts of mission vulnerabilities,» the report said.
While surface temperature show a significant warming over western Himalayas in the last few decades, the
observed regional
precipitation changes are irregular and not spatially coherent.
She continues by
observing that «it is likely that both extreme weather events (storms, floods, heat waves) and
changes in mean temperatures,
precipitation and sea - levels will in many cases contribute to increasing levels of mobility.»
«We show that anthropogenic forcing has had a detectable influence on
observed changes in average
precipitation within latitudinal bands, and that these
changes can not be explained by internal climate variability or natural forcing.
The combination of width, density, and isotope analysis offers a powerful set of independent but mutually reinforcing tools for reconstructing climate because the effects of temperature and
precipitation can be distinguished, and seasonal
changes can be
observed.
Anthropogenic influences have contributed to
observed increases in atmospheric moisture content in the atmosphere (medium confidence), to global - scale
changes in
precipitation patterns over land (medium confidence), to intensification of heavy
precipitation over land regions where data are sufficient (medium confidence), and to
changes in surface and subsurface ocean salinity (very likely).
«What causes the
observed changes in
precipitation and temperature is not something we have addressed because of the difficulties in doing so just based on observational records,» Villarini says.
Controlling for
observed conditions, beliefs about global climate
change had a large effect on perceptions of seasonal temperature, and smaller effects on perceptions of seasonal
precipitation.»
Observed changes in
precipitation and aspects of surface hydrology are described in more detail by Trenberth et al. (2007), Section 3.3.
[10]
Observed trends in
precipitation and floods over Europe are in line with these future projections, however their climate
change signal is quite complex.
«With an early arrival of monsoon - like atmospheric circulation in June, the heavy
precipitation that occurred in northern India was a once - in - a-century event; however, analyses of
observed and simulated June
precipitation provide evidence that human - caused climate
change has increased the likelihood of such an event.»