Temperature Change

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Brian J Soden - One of the best experts on this subject based on the ideXlab platform.

  • effect of remote sea surface Temperature Change on tropical cyclone potential intensity
    Nature, 2007
    Co-Authors: Gabriel A Vecchi, Brian J Soden
    Abstract:

    The response of tropical cyclone activity to global warming is poorly understood. It is often assumed that warmer sea surface Temperatures favour cyclone development and intensification, but this may not be the case as so many other factors are involved. Gabriel Vecchi and Brian Soden explore the relationship between Changes in sea-surface Temperature and a measure called 'tropical cyclone potential intensity', which provides an upper limit on cyclone intensity. They find that Changes in potential intensity are closely related to the regional structure of warming, rather than local sea surface Temperature — regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. This suggests that the response of tropical cyclone activity to natural climate variations, which tend to involve localized Changes in sea surface Temperature, may be larger (per unit local sea surface Temperature Change) than the response to the more uniform patterns of warming induced by greenhouse gases. The relationship between Changes in sea surface Temperature and a measure called 'tropical cyclone potential intensity', which provides an upper bound on cyclone intensity, is explored. It is found that Changes in potential intensity are closely related to the regional structure of warming, rather than local sea surface Temperature — regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. The response of tropical cyclone activity to global warming is widely debated1,2,3,4,5,6,7,8,9,10. It is often assumed that warmer sea surface Temperatures provide a more favourable environment for the development and intensification of tropical cyclones, but cyclone genesis and intensity are also affected by the vertical thermodynamic properties of the atmosphere1,10,11,12,13. Here we use climate models and observational reconstructions to explore the relationship between Changes in sea surface Temperature and tropical cyclone ‘potential intensity’—a measure that provides an upper bound on cyclone intensity10,11,12,13,14 and can also reflect the likelihood of cyclone development15,16. We find that Changes in local sea surface Temperature are inadequate for characterizing even the sign of Changes in potential intensity, but that long-term Changes in potential intensity are closely related to the regional structure of warming; regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. We use this relationship to reconstruct Changes in potential intensity over the twentieth century from observational reconstructions of sea surface Temperature. We find that, even though tropical Atlantic sea surface Temperatures are currently at a historical high, Atlantic potential intensity probably peaked in the 1930s and 1950s, and recent values are near the historical average. Our results indicate that—per unit local sea surface Temperature Change—the response of tropical cyclone activity to natural climate variations, which tend to involve localized Changes in sea surface Temperature, may be larger than the response to the more uniform patterns of greenhouse-gas-induced warming.

  • effect of remote sea surface Temperature Change on tropical cyclone potential intensity
    Nature, 2007
    Co-Authors: Gabriel A Vecchi, Brian J Soden
    Abstract:

    The response of tropical cyclone activity to global warming is widely debated. It is often assumed that warmer sea surface Temperatures provide a more favourable environment for the development and intensification of tropical cyclones, but cyclone genesis and intensity are also affected by the vertical thermodynamic properties of the atmosphere. Here we use climate models and observational reconstructions to explore the relationship between Changes in sea surface Temperature and tropical cyclone 'potential intensity'--a measure that provides an upper bound on cyclone intensity and can also reflect the likelihood of cyclone development. We find that Changes in local sea surface Temperature are inadequate for characterizing even the sign of Changes in potential intensity, but that long-term Changes in potential intensity are closely related to the regional structure of warming; regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. We use this relationship to reconstruct Changes in potential intensity over the twentieth century from observational reconstructions of sea surface Temperature. We find that, even though tropical Atlantic sea surface Temperatures are currently at a historical high, Atlantic potential intensity probably peaked in the 1930s and 1950s, and recent values are near the historical average. Our results indicate that--per unit local sea surface Temperature Change--the response of tropical cyclone activity to natural climate variations, which tend to involve localized Changes in sea surface Temperature, may be larger than the response to the more uniform patterns of greenhouse-gas-induced warming.

Gabriel A Vecchi - One of the best experts on this subject based on the ideXlab platform.

  • effect of remote sea surface Temperature Change on tropical cyclone potential intensity
    Nature, 2007
    Co-Authors: Gabriel A Vecchi, Brian J Soden
    Abstract:

    The response of tropical cyclone activity to global warming is poorly understood. It is often assumed that warmer sea surface Temperatures favour cyclone development and intensification, but this may not be the case as so many other factors are involved. Gabriel Vecchi and Brian Soden explore the relationship between Changes in sea-surface Temperature and a measure called 'tropical cyclone potential intensity', which provides an upper limit on cyclone intensity. They find that Changes in potential intensity are closely related to the regional structure of warming, rather than local sea surface Temperature — regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. This suggests that the response of tropical cyclone activity to natural climate variations, which tend to involve localized Changes in sea surface Temperature, may be larger (per unit local sea surface Temperature Change) than the response to the more uniform patterns of warming induced by greenhouse gases. The relationship between Changes in sea surface Temperature and a measure called 'tropical cyclone potential intensity', which provides an upper bound on cyclone intensity, is explored. It is found that Changes in potential intensity are closely related to the regional structure of warming, rather than local sea surface Temperature — regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. The response of tropical cyclone activity to global warming is widely debated1,2,3,4,5,6,7,8,9,10. It is often assumed that warmer sea surface Temperatures provide a more favourable environment for the development and intensification of tropical cyclones, but cyclone genesis and intensity are also affected by the vertical thermodynamic properties of the atmosphere1,10,11,12,13. Here we use climate models and observational reconstructions to explore the relationship between Changes in sea surface Temperature and tropical cyclone ‘potential intensity’—a measure that provides an upper bound on cyclone intensity10,11,12,13,14 and can also reflect the likelihood of cyclone development15,16. We find that Changes in local sea surface Temperature are inadequate for characterizing even the sign of Changes in potential intensity, but that long-term Changes in potential intensity are closely related to the regional structure of warming; regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. We use this relationship to reconstruct Changes in potential intensity over the twentieth century from observational reconstructions of sea surface Temperature. We find that, even though tropical Atlantic sea surface Temperatures are currently at a historical high, Atlantic potential intensity probably peaked in the 1930s and 1950s, and recent values are near the historical average. Our results indicate that—per unit local sea surface Temperature Change—the response of tropical cyclone activity to natural climate variations, which tend to involve localized Changes in sea surface Temperature, may be larger than the response to the more uniform patterns of greenhouse-gas-induced warming.

  • effect of remote sea surface Temperature Change on tropical cyclone potential intensity
    Nature, 2007
    Co-Authors: Gabriel A Vecchi, Brian J Soden
    Abstract:

    The response of tropical cyclone activity to global warming is widely debated. It is often assumed that warmer sea surface Temperatures provide a more favourable environment for the development and intensification of tropical cyclones, but cyclone genesis and intensity are also affected by the vertical thermodynamic properties of the atmosphere. Here we use climate models and observational reconstructions to explore the relationship between Changes in sea surface Temperature and tropical cyclone 'potential intensity'--a measure that provides an upper bound on cyclone intensity and can also reflect the likelihood of cyclone development. We find that Changes in local sea surface Temperature are inadequate for characterizing even the sign of Changes in potential intensity, but that long-term Changes in potential intensity are closely related to the regional structure of warming; regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. We use this relationship to reconstruct Changes in potential intensity over the twentieth century from observational reconstructions of sea surface Temperature. We find that, even though tropical Atlantic sea surface Temperatures are currently at a historical high, Atlantic potential intensity probably peaked in the 1930s and 1950s, and recent values are near the historical average. Our results indicate that--per unit local sea surface Temperature Change--the response of tropical cyclone activity to natural climate variations, which tend to involve localized Changes in sea surface Temperature, may be larger than the response to the more uniform patterns of greenhouse-gas-induced warming.

James Hansen - One of the best experts on this subject based on the ideXlab platform.

  • Global surface Temperature Change
    Rev. Geophys., 2010
    Co-Authors: James Hansen, Reto Ruedy, Makiko Sato, Ken Lo
    Abstract:

    We update the Goddard Institute for Space Studies (GISS) analysis of global surface Temperature Change, compare alternative analyses, and address questions about perception and reality of global warming. Satellite-observed night lights are used to identify measurement stations located in extreme darkness and adjust Temperature trends of urban and periurban stations for nonclimatic factors, verifying that urban effects on analyzed global Change are small. Because the GISS analysis combines available sea surface Temperature records with meteorological station measurements, we test alternative choices for the ocean data, showing that global Temperature Change is sensitive to estimated Temperature Change in polar regions where observations are limited. We use simple 12 month (and n × 12) running means to improve the information content in our Temperature graphs. Contrary to a popular misconception, the rate of warming has not declined. Global Temperature is rising as fast in the past decade as in the prior 2 decades, despite year-to-year fluctuations associated with the El Niño-La Niña cycle of tropical ocean Temperature. Record high global 12 month running mean Temperature for the period with instrumental data was reached in 2010.

  • Global Temperature Change
    Proceedings of the National Academy of Sciences of the United States of America, 2006
    Co-Authors: James Hansen, Reto Ruedy, Makiko Sato, David W. Lea, Martin Medina-elizade
    Abstract:

    lobal Temperature is a popular metric for summarizing the state of global climate. Climate effects are felt locally, but the global distribution of climate response to many global climate forcings is reasonably congruent in climate models (1), suggesting that the global metric is surprisingly useful. We will argue further, consistent with earlier discussion (2, 3), that measurements in the Western Pacific and Indian Oceans provide a good indication of global Temperature Change. WefirstupdateouranalysisofsurfaceTemperatureChangebased on instrumental data and compare observed Temperature Change with predictions of global climate Change made in the 1980s. We then examine current Temperature anomalies in the tropical Pacific Ocean and discuss their possible significance. Finally, we compare paleoclimate and recent data, using the Earth's history to estimate the magnitude of global warming that is likely to constitute dan-

  • a closer look at united states and global surface Temperature Change
    Journal of Geophysical Research, 2001
    Co-Authors: James Hansen, Reto Ruedy, Makiko Sato, M Imhoff, W Lawrence, David R Easterling, Thomas C Peterson, Thomas R Karl
    Abstract:

    We compare the United States and global surface air Temperature Changes of the past century using the current Goddard Institute for Space Studies (GISS) analysis and the U.S. Historical Climatology Network (USHCN) record [Karl et al., 1990]. Changes in the GISS analysis subsequent to the documentation by Hansen et al. [1999] are as follows: (1) incorporation of corrections for time-of-observation bias and station history adjustments in the United States based on Easterling et al. [1996a], (2) reclassification of rural, small-town, and urban stations in the United States, southern Canada, and northern Mexico based on satellite measurements of night light intensity [Imhoff et al., 1997], and (3) a more flexible urban adjustment than that employed by Hansen et al. [1999], including reliance on only unlit stations in the United States and rural stations in the rest of the world for determining long-term trends. We find evidence of local human effects (“urban warming”) even in suburban and small-town surface air Temperature records, but the effect is modest in magnitude and conceivably could be an artifact of inhomogeneities in the station records. We suggest further studies, including more complete satellite night light analyses, which may clarify the potential urban effect. There are inherent uncertainties in the long-term Temperature Change at least of the order of 0.1°C for both the U.S. mean and the global mean. Nevertheless, it is clear that the post-1930s cooling was much larger in the United States than in the global mean. The U.S. mean Temperature has now reached a level comparable to that of the 1930s, while the global Temperature is now far above the levels earlier in the century. The successive periods of global warming (1900–1940), cooling (1940–1965), and warming (1965–2000) in the 20th century show distinctive patterns of Temperature Change suggestive of roles for both climate forcings and dynamical variability. The U.S. was warm in 2000 but cooler than the warmest years in the 1930s and 1990s. Global Temperature was moderately high in 2000 despite a lingering La Nina in the Pacific Ocean.

  • GISS analysis of surface Temperature Change
    Journal of Geophysical Research: Atmospheres, 1999
    Co-Authors: James Hansen, Reto Ruedy, J. Glascoe, Makiko Sato
    Abstract:

    We describe the current GISS analysis of surface Temperature Change for the period 1880-1999 based primarily on meteorological station measurements. The global surface Temperature in 1998 was the warmest in the period of instrumental data. The rate of Temperature Change was higher in the past 25 years than at any previous time in the period of instrumental data. The warmth of 1998 was too large and pervasive to be fully accounted for by the recent El Nino. Despite cooling in the first half of 1999, we suggest that the mean global Temperature, averaged over 2-3 years, has moved to a higher level, analogous to the increase that occurred in the late 1970s. Warming in the United States over the past 50 years has been smaller than in most of the world, and over that period there was a slight cooling trend in the eastern United States and the neighboring Atlantic Ocean. The spatial and temporal patterns of the Temperature Change suggest that more than one mechanism was involved in this regional cooling. The cooling trend in the United States, which began after the 1930s and is associated with ocean Temperature Change patterns, began to reverse after 1979. We suggest that further warming in the United States to a level rivaling the 1930s is likely in the next decade, but reliable prediction requires better understanding of decadal oscillations of ocean Temperature.

Makiko Sato - One of the best experts on this subject based on the ideXlab platform.

  • Global surface Temperature Change
    Rev. Geophys., 2010
    Co-Authors: James Hansen, Reto Ruedy, Makiko Sato, Ken Lo
    Abstract:

    We update the Goddard Institute for Space Studies (GISS) analysis of global surface Temperature Change, compare alternative analyses, and address questions about perception and reality of global warming. Satellite-observed night lights are used to identify measurement stations located in extreme darkness and adjust Temperature trends of urban and periurban stations for nonclimatic factors, verifying that urban effects on analyzed global Change are small. Because the GISS analysis combines available sea surface Temperature records with meteorological station measurements, we test alternative choices for the ocean data, showing that global Temperature Change is sensitive to estimated Temperature Change in polar regions where observations are limited. We use simple 12 month (and n × 12) running means to improve the information content in our Temperature graphs. Contrary to a popular misconception, the rate of warming has not declined. Global Temperature is rising as fast in the past decade as in the prior 2 decades, despite year-to-year fluctuations associated with the El Niño-La Niña cycle of tropical ocean Temperature. Record high global 12 month running mean Temperature for the period with instrumental data was reached in 2010.

  • Global Temperature Change
    Proceedings of the National Academy of Sciences of the United States of America, 2006
    Co-Authors: James Hansen, Reto Ruedy, Makiko Sato, David W. Lea, Martin Medina-elizade
    Abstract:

    lobal Temperature is a popular metric for summarizing the state of global climate. Climate effects are felt locally, but the global distribution of climate response to many global climate forcings is reasonably congruent in climate models (1), suggesting that the global metric is surprisingly useful. We will argue further, consistent with earlier discussion (2, 3), that measurements in the Western Pacific and Indian Oceans provide a good indication of global Temperature Change. WefirstupdateouranalysisofsurfaceTemperatureChangebased on instrumental data and compare observed Temperature Change with predictions of global climate Change made in the 1980s. We then examine current Temperature anomalies in the tropical Pacific Ocean and discuss their possible significance. Finally, we compare paleoclimate and recent data, using the Earth's history to estimate the magnitude of global warming that is likely to constitute dan-

  • a closer look at united states and global surface Temperature Change
    Journal of Geophysical Research, 2001
    Co-Authors: James Hansen, Reto Ruedy, Makiko Sato, M Imhoff, W Lawrence, David R Easterling, Thomas C Peterson, Thomas R Karl
    Abstract:

    We compare the United States and global surface air Temperature Changes of the past century using the current Goddard Institute for Space Studies (GISS) analysis and the U.S. Historical Climatology Network (USHCN) record [Karl et al., 1990]. Changes in the GISS analysis subsequent to the documentation by Hansen et al. [1999] are as follows: (1) incorporation of corrections for time-of-observation bias and station history adjustments in the United States based on Easterling et al. [1996a], (2) reclassification of rural, small-town, and urban stations in the United States, southern Canada, and northern Mexico based on satellite measurements of night light intensity [Imhoff et al., 1997], and (3) a more flexible urban adjustment than that employed by Hansen et al. [1999], including reliance on only unlit stations in the United States and rural stations in the rest of the world for determining long-term trends. We find evidence of local human effects (“urban warming”) even in suburban and small-town surface air Temperature records, but the effect is modest in magnitude and conceivably could be an artifact of inhomogeneities in the station records. We suggest further studies, including more complete satellite night light analyses, which may clarify the potential urban effect. There are inherent uncertainties in the long-term Temperature Change at least of the order of 0.1°C for both the U.S. mean and the global mean. Nevertheless, it is clear that the post-1930s cooling was much larger in the United States than in the global mean. The U.S. mean Temperature has now reached a level comparable to that of the 1930s, while the global Temperature is now far above the levels earlier in the century. The successive periods of global warming (1900–1940), cooling (1940–1965), and warming (1965–2000) in the 20th century show distinctive patterns of Temperature Change suggestive of roles for both climate forcings and dynamical variability. The U.S. was warm in 2000 but cooler than the warmest years in the 1930s and 1990s. Global Temperature was moderately high in 2000 despite a lingering La Nina in the Pacific Ocean.

  • GISS analysis of surface Temperature Change
    Journal of Geophysical Research: Atmospheres, 1999
    Co-Authors: James Hansen, Reto Ruedy, J. Glascoe, Makiko Sato
    Abstract:

    We describe the current GISS analysis of surface Temperature Change for the period 1880-1999 based primarily on meteorological station measurements. The global surface Temperature in 1998 was the warmest in the period of instrumental data. The rate of Temperature Change was higher in the past 25 years than at any previous time in the period of instrumental data. The warmth of 1998 was too large and pervasive to be fully accounted for by the recent El Nino. Despite cooling in the first half of 1999, we suggest that the mean global Temperature, averaged over 2-3 years, has moved to a higher level, analogous to the increase that occurred in the late 1970s. Warming in the United States over the past 50 years has been smaller than in most of the world, and over that period there was a slight cooling trend in the eastern United States and the neighboring Atlantic Ocean. The spatial and temporal patterns of the Temperature Change suggest that more than one mechanism was involved in this regional cooling. The cooling trend in the United States, which began after the 1930s and is associated with ocean Temperature Change patterns, began to reverse after 1979. We suggest that further warming in the United States to a level rivaling the 1930s is likely in the next decade, but reliable prediction requires better understanding of decadal oscillations of ocean Temperature.

J F B Mitchell - One of the best experts on this subject based on the ideXlab platform.

  • estimation of natural and anthropogenic contributions to twentieth century Temperature Change
    Journal of Geophysical Research, 2002
    Co-Authors: S F B Tett, Peter A Stott, Myles R Allen, William Ingram, J F B Mitchell, Gareth S Jones, David C Hill, T C Johns
    Abstract:

    [1] Using a coupled atmosphere/ocean general circulation model, we have simulated the climatic response to natural and anthropogenic forcings from 1860 to 1997. The model, HadCM3, requires no flux adjustment and has an interactive sulphur cycle, a simple parameterization of the effect of aerosols on cloud albedo (first indirect effect), and a radiation scheme that allows explicit representation of well-mixed greenhouse gases. Simulations were carried out in which the model was forced with Changes in natural forcings (solar irradiance and stratospheric aerosol due to explosive volcanic eruptions), well-mixed greenhouse gases alone, tropospheric anthropogenic forcings (tropospheric ozone, well-mixed greenhouse gases, and the direct and first indirect effects of sulphate aerosol), and anthropogenic forcings (tropospheric anthropogenic forcings and stratospheric ozone decline). Using an “optimal detection” methodology to examine Temperature Changes near the surface and throughout the free atmosphere, we find that we can detect the effects of Changes in well-mixed greenhouse gases, other anthropogenic forcings (mainly the effects of sulphate aerosols on cloud albedo), and natural forcings. Thus these have all had a significant impact on Temperature. We estimate the linear trend in global mean near-surface Temperature from well-mixed greenhouse gases to be 0.9 ± 0.24 K/century, offset by cooling from other anthropogenic forcings of 0.4 ± 0.26 K/century, giving a total anthropogenic warming trend of 0.5 ± 0.15 K/century. Over the entire century, natural forcings give a linear trend close to zero. We found no evidence that simulated Changes in near-surface Temperature due to anthropogenic forcings were in error. However, the simulated tropospheric response, since the 1960s, is ∼50% too large. Our analysis suggests that the early twentieth century warming can best be explained by a combination of warming due to increases in greenhouse gases and natural forcing, some cooling due to other anthropogenic forcings, and a substantial, but not implausible, contribution from internal variability. In the second half of the century we find that the warming is largely caused by Changes in greenhouse gases, with Changes in sulphates and, perhaps, volcanic aerosol offsetting approximately one third of the warming. Warming in the troposphere, since the 1960s, is probably mainly due to anthropogenic forcings, with a negligible contribution from natural forcings.

  • attribution of twentieth century Temperature Change to natural and anthropogenic causes
    Climate Dynamics, 2001
    Co-Authors: Peter A Stott, S F B Tett, Myles R Allen, William Ingram, Gareth S Jones, J F B Mitchell
    Abstract:

    We analyse possible causes of twentieth century near-surface Temperature Change. We use an “optimal detection” methodology to compare seasonal and annual data from the coupled atmosphere-ocean general circulation model HadCM2 with observations averaged over a range of spatial and temporal scales. The results indicate that the increases in Temperature observed in the latter half of the century have been caused by warming from anthropogenic increases in greenhouse gases offset by cooling from tropospheric sulfate aerosols rather than natural variability, either internal or externally forced. We also find that greenhouse gases are likely to have contributed significantly to the warming in the first half of the century. In addition, natural effects may have contributed to this warming. Assuming one particular reconstruction of total solar irradiance to be correct implies, when we take the seasonal cycle into account, that solar effects have contributed significantly to the warming observed in the early part of the century, regardless of any relative error in the amplitudes of the anthropogenic forcings prescribed in the model. However, this is not the case with an alternative reconstruction of total solar irradiance, based more on the amplitude than the length of the solar cycle. We also find evidence for volcanic influences on twentieth century near-surface Temperatures. The signature of the eruption of Mount Pinatubo is detected using annual-mean data. We also find evidence for a volcanic influence on warming in the first half of the century associated with a reduction in mid-century volcanism.

  • causes of twentieth century Temperature Change near the earth s surface
    Nature, 1999
    Co-Authors: S F B Tett, Peter A Stott, Myles R Allen, William Ingram, J F B Mitchell
    Abstract:

    Observations of the Earth's near-surface Temperature show a global-mean Temperature increase of approximately 0.6 K since 1900 (ref. 1), occurring from 1910 to 1940 and from 1970 to the present. The Temperature Change over the past 30–50 years is unlikely to be entirely due to internal climate variability2,3,4 and has been attributed to Changes in the concentrations of greenhouse gases and sulphate aerosols5 due to human activity. Attribution of the warming early in the century has proved more elusive. Here we present a quantification of the possible contributions throughout the century from the four components most likely to be responsible for the large-scale Temperature Changes, of which two vary naturally (solar irradiance and stratospheric volcanic aerosols) and two have Changed decisively due to anthropogenic influence (greenhouse gases and sulphate aerosols). The patterns of time/space Changes in near-surface Temperature due to the separate forcing components are simulated with a coupled atmosphere–ocean general circulation model, and a linear combination of these is fitted to observations. Thus our analysis is insensitive to errors in the simulated amplitude of these responses. We find that solar forcing may have contributed to the Temperature Changes early in the century, but anthropogenic causes combined with natural variability would also present a possible explanation. For the warming from 1946 to 1996 regardless of any possible amplification of solar or volcanic influence, we exclude purely natural forcing, and attribute it largely to the anthropogenic components.