Not exact matches
Extremes in local and regional weather
patterns and climate
variability have disrupted agricultural production in the
past; climate - related temperature rise is expected to increasingly affect crop yields in many regions
of the world.
Despite large year - to - year
variability of temperature, decadal averages reveal isotherms (lines
of a given average temperature) moving poleward at a typical rate
of the order
of 100 km / decade in the
past three decades [101], although the range shifts for specific species follow more complex
patterns [102].
Mike's work, like that
of previous award winners, is diverse, and includes pioneering and highly cited work in time series analysis (an elegant use
of Thomson's multitaper spectral analysis approach to detect spatiotemporal oscillations in the climate record and methods for smoothing temporal data), decadal climate
variability (the term «Atlantic Multidecadal Oscillation» or «AMO» was coined by Mike in an interview with Science's Richard Kerr about a paper he had published with Tom Delworth
of GFDL showing evidence in both climate model simulations and observational data for a 50 - 70 year oscillation in the climate system; significantly Mike also published work with Kerry Emanuel in 2006 showing that the AMO concept has been overstated as regards its role in 20th century tropical Atlantic SST changes, a finding recently reaffirmed by a study published in Nature), in showing how changes in radiative forcing from volcanoes can affect ENSO, in examining the role
of solar variations in explaining the
pattern of the Medieval Climate Anomaly and Little Ice Age, the relationship between the climate changes
of past centuries and phenomena such as Atlantic tropical cyclones and global sea level, and even a bit
of work in atmospheric chemistry (an analysis
of beryllium - 7 measurements).
Ironically, while some continue to attack this nearly decade - old work, the actual scientific community has moved well beyond the earlier studies, focusing now on the detailed
patterns of modeled and reconstructed climate changes in
past centuries, and insights into the roles
of external forcing and internal modes
of variability (such as the North Atlantic Oscillation or «NAO» and the «El Nino / Southern Oscillation» or «ENSO») in explaining this
past variability.
Even if it could be shown that climate is more sensitive to solar
variability than the strict radiative forcing would suggest (along the lines
of Shindell et al) one would still have to contend with the fact that we know the solar
variability for the
past fifty years quite well, and it does not do the kind
of things necessary to give the present warming
pattern.
The stadium wave holds promise in putting into perspective numerous observations
of climate behavior, such as regional
patterns of decadal
variability in drought and hurricane activity, the researchers say, but a complete understanding
of past climate
variability and projections
of future climate change requires integrating the stadium - wave signal with external climate forcing from the sun, volcanoes and anthropogenic forcing.
If
past patterns of precipitation
variability remain stable in the near term, then it is probable that precipitation and flows in the Salt - Verde watersheds will shift into wetter conditions within the timeframe examined in this study [66].
This Section places particular emphasis on current knowledge
of past changes in key climate variables: temperature, precipitation and atmospheric moisture, snow cover, extent
of land and sea ice, sea level,
patterns in atmospheric and oceanic circulation, extreme weather and climate events, and overall features
of the climate
variability.
My observations from your graph line are that there has been a break in the 200 - year trend
of rising and falling, as
of the 1960's becoming rising only, which had not happened on any span even half so long previously, and which does not resemble the
past pattern of variability of 11 - year trends.
Despite large year - to - year
variability of temperature, decadal averages reveal isotherms (lines
of a given average temperature) moving poleward at a typical rate
of the order
of 100 km / decade in the
past three decades [101], although the range shifts for specific species follow more complex
patterns [102].
Over the
past 60 years, Alaska has warmed more than twice as rapidly as the rest
of the United States, with state - wide average annual air temperature increasing by 3 °F and average winter temperature by 6 °F, with substantial year - to - year and regional
variability.1 Most
of the warming occurred around 1976 during a shift in a long - lived climate
pattern (the Pacific Decadal Oscillation [PDO]-RRB- from a cooler
pattern to a warmer one.
Given that the
past 30 — 50 years is a relatively short period for evaluating long - term trends, the SST trends themselves could be viewed as a manifestation
of large - scale modes
of multidecadal Pacific
variability (e.g. Zhang et al. 1997; Deser et al. 2004) or as part
of the century scale positive SST trends associated with climate change (e.g. Deser et al. 2010); it is likely that both multidecadal climate
variability and climate change have contributed to the SST trend
pattern evident in Fig. 9 and used to force the model.
«How can we use the spatial
pattern of the surface temperature evolution to help determine how much
of the warming over the
past century was forced by increases in the well - mixed greenhouse gases (WMGGs: CO2, CH4, N2O, CFCs), assuming as little as possible about the non-WMGG forcing and internal
variability.»
The mean state
of ENSO, its global
patterns of influence, amplitude
of interannual
variability, and frequency
of extreme events show considerable multidecadal and century - scale
variability over the
past several centuries.»
These range from simple averaging
of regional data and scaling
of the resulting series so that its mean and standard deviation match those
of the observed record over some period
of overlap (Jones et al., 1998; Crowley and Lowery, 2000), to complex climate field reconstruction, where large - scale modes
of spatial climate
variability are linked to
patterns of variability in the proxy network via a multivariate transfer function that explicitly provides estimates
of the spatio - temporal changes in
past temperatures, and from which large - scale average temperature changes are derived by averaging the climate estimates across the required region (Mann et al., 1998; Rutherford et al., 2003, 2005).
The
pattern of modeled surface temperature changes induced by solar
variability is well correlated with observed global warming over the first half
of the 20th century, but not with the more rapid warming seen over the
past three decades.
Tim Barnett: ««What we hope is that the current
patterns of temperature change prove distinctive, quite different from the
patterns of natural
variability in the
past,» Barnett told [Fred Pearce] in 1996.