Measurements show that the Earth’s global-average near-surface temperature has increased by about 0.8℃ since the 19th century. It is critically important to determine whether this global warming is due to natural ca...Measurements show that the Earth’s global-average near-surface temperature has increased by about 0.8℃ since the 19th century. It is critically important to determine whether this global warming is due to natural causes, as contended by climate contrarians, or by human activities, as argued by the Intergovernmental Panel on Climate Change. This study updates our earlier calculations which showed that the observed global warming was predominantly human-caused. Two independent methods are used to analyze the temperature measurements: Singular Spectrum Analysis and Climate Model Simulation. The concurrence of the results of the two methods, each using 13 additional years of temperature measurements from 1998 through 2010, shows that it is humanity, not nature, that has increased the Earth’s global temperature since the 19th century. Humanity is also responsible for the most recent period of warming from 1976 to 2010. Internal climate variability is primarily responsible for the early 20th century warming from 1904 to 1944 and the subsequent cooling from 1944 to 1976. It is also found that the equilibrium climate sensitivity is on the low side of the range given in the IPCC Fourth Assessment Report.展开更多
We apply Singular Spectrum Analysis to four datasets of observed global-mean near-surface temperature from start year to through 2012: HadCRU (to = 1850), NOAA (to = 1880), NASA (to = 1880), and JMA (to = 1891). For e...We apply Singular Spectrum Analysis to four datasets of observed global-mean near-surface temperature from start year to through 2012: HadCRU (to = 1850), NOAA (to = 1880), NASA (to = 1880), and JMA (to = 1891). For each dataset, SSA reveals a trend of increasing temperature and several quasi-periodic oscillations (QPOs). QPOs 1, 2 and 3 are predictable on a year-by-year basis by sine waves with periods/amplitudes of: 1) 62.4 years/0.11°C;2) 20.1 to 21.4 years/0.04°C to 0.05°C;and 3) 9.1 to 9.2 years/0.03°C to 0.04°C. The remainder of the natur°l variability is not predictable on a year-by-year basis. We represent this noise by its 90 percent confidence interval. We combine the predictable and unpredictable natural variability with the temperature changes caused by the 11-year solar cycle and humanity, the latter for both the Reference and Revised-Fair-Plan scenarios for future emissions of greenhouse gases. The resulting temperature departures show that we have moved from the first phase of learning—Ignorance—through the second phase—Uncertainty—and are now entering the third phase—Resolution—when the human-caused signal is much larger than the natural variability. Accordingly, it is now time to transition to the post-fossil-fuel age by phasing out fossil-fuel emissions from 2020 through 2100.展开更多
The most recent US Congressional climate bill, H.R.5271 in 2014, proposes to reduce US emissions of carbon dioxide relative to their 2005 value by 80% in 2050. This bill does not provide a rationale for this rapid pha...The most recent US Congressional climate bill, H.R.5271 in 2014, proposes to reduce US emissions of carbon dioxide relative to their 2005 value by 80% in 2050. This bill does not provide a rationale for this rapid phase down of CO2 emissions. In 2012, we crafted a Fair Plan to Safeguard Earth’s Climate such that: 1) The cumulative trade-adjusted CO2 emissions by the developing countries equal the cumulative trade-adjusted CO2 emissions by the developed countries;2) The maximum global warming above preindustrial temperature does not exceed the 2°C (3.6°F) chosen by the United Nations Framework Convention on Climate Change “to prevent dangerous anthropogenic interference with the climate system”;and 3) The phase out of CO2 emissions begins as late as possible in the 21st century and proceeds at the slowest possible pace, consistent with objectives 1 and 2. The Fair Plan begins in 2020 and reduces the world’s emissions to zero in 2100. In the Fair Plan the emissions of the developed countries, including the United States, reach 80% below their 2005 values in 2094, that is, 44 years later than proposed by H.R.5271. While it is imperative that humanity begins to wean itself from fossil fuels no later than 2020, the transition from fossil to non-fossil energy need not be completed before 2100 if all countries follow their Fair Plan trajectories.展开更多
Earth is the only habitable planet in the solar system and beyond in interstellar space for a distance that would take us at least 80,000 years to traverse at the speed of Voyager 1. Thus our home planet is “This Isl...Earth is the only habitable planet in the solar system and beyond in interstellar space for a distance that would take us at least 80,000 years to traverse at the speed of Voyager 1. Thus our home planet is “This Island Earth”. Here we use our Simple (engineering-type) Climate Model to calculate the change in global-mean near-surface air temperature from 1765 through the third millennium for historical emissions and two scenarios of future emissions of greenhouse gases: (1) a Reference scenario of unabated emissions, and (2) our Fair Plan scenario wherein emissions are phased out to zero from 2020 to 2100. The temperature change for the Reference cases increases to 5.2°C (9.4°F) in 2225 and remains there for at least 40 human generations. By design, the temperature change for the Fair Plan increases only to 2°C (3.6°F)—the limit adopted by the UN Framework Convention on Climate Change “to prevent dangerous anthropogenic interference with the climate system”—in 2082 and thereafter decreases through the remainder of the millennium. Accordingly, we need to adopt the Fair Plan to safeguard the climate of “This Island Earth”.展开更多
Previously we have used Singular Spectrum Analysis (SSA) to deconstruct the global-mean near-surface temperature observations of the Hadley Centre—Climate Research Unit that extend from 1850 through 2012. While SSA i...Previously we have used Singular Spectrum Analysis (SSA) to deconstruct the global-mean near-surface temperature observations of the Hadley Centre—Climate Research Unit that extend from 1850 through 2012. While SSA is a very powerful tool, it is rather like a statistical “black box” that gives little intuition about its results. Accordingly, here we use the simplest statistical tool to provide such intuition, the Simple Moving Average (SMA). Firstly we use a 21-year SMA. This reveals a nonlinear trend and an oscillation of about 60 years' length. Secondly we use a 61-year SMA on the raw observations. This yields a nonlinear trend. We subtract this trend from the raw observations and apply a 21-year SMA. This yields a Quasi-periodic Oscillation (QPO) with a period and amplitude of about 62.4 years and 0.11°C. This is the QPO we discovered in our 1994 Nature paper, which has come to be called the Atlantic Multidecadal Oscillation. We then subtract QPO-1 from the detrended observations and apply an 11-year SMA. This yields QPO-2 with a period and amplitude of about 21.0 years and 0.04°C. We subtract QPO-2 from the detrended observations minus QPO-1 and apply a 3-year SMA. This yields QPO-3 with a period and amplitude of about 9.1 years and 0.03°C. QPOs 1, 2 and 3 are sufficiently regular in period and amplitude that we fit them by sine waves, thereby yielding the above periods and amplitudes. We then subtract QPO-3 from the detrended observations minus QPOs 1 and 2. The result is too irregular in period and amplitude to be fit by a sine wave. Accordingly we represent this unpredictable part of the temperature observations by a Gaussian probability distribution (GPD) with a mean of zero and standard deviation of 0.08°C. The sum of QPOs 1, 2 and 3 plus the GPD can be used to project the natural variability of the global-mean near-surface temperature to add to, and be compared with, the continuing temperature trend caused predominantly by humanity’s continuing combustion of fossil fuels.展开更多
Earth’s climate future is in the hands of humanity. If emissions of greenhouse gases remain unabated, Earth’s climate will return to the climate of the Late Eocene, 35 million years ago, when sea level was 73 meters...Earth’s climate future is in the hands of humanity. If emissions of greenhouse gases remain unabated, Earth’s climate will return to the climate of the Late Eocene, 35 million years ago, when sea level was 73 meters (240 feet) higher than today. Should that occur, many coastal cities around the world would be inundated. Moreover the Global Warming of this unabated Reference case will be comparable to the Global Warming from the Last Glacial Maximum 21,000 years ago to the beginning of the Holocene interglacial climate 11,000 years ago. However, this human-caused Global Warming would occur 50 times faster than that caused by nature. Alternatively, humanity can mitigate greenhouse-gas emissions to keep Global Warming below the 2°C maximum adopted by the United Nations Framework Convention on Climate Change “to prevent dangerous anthropogenic interference with the climate system”. This mitigation can either be done rapidly, as in the “80/50” Plan to reduce greenhouse-gas emissions 80% by 2050, or much more slowly, from 2020 to 2100, as in the Fair Plan to Safeguard Earth’s Climate. The Fair Plan is a compromise between doing nothing, as in the Reference case, and rapidly reducing greenhouse-gas emissions, as in the 80/50 Plan. Regardless of the Plan chosen to reduce greenhouse-gas emissions to keep Global Warming below the UNFCCC limit of 2°C (3.6°F), it should not be tantamount to our saying to one of our planetary spacecraft, Bon Voyage, call us when you get to your planetary destination. Rather, as with our spacecraft, the chosen climate-change policy should be monitored throughout the 21st century and Midcourse Corrections made thereto as needed to keep our “Climate Spacecraft” on track to achieve its “Climate Target”.展开更多
文摘Measurements show that the Earth’s global-average near-surface temperature has increased by about 0.8℃ since the 19th century. It is critically important to determine whether this global warming is due to natural causes, as contended by climate contrarians, or by human activities, as argued by the Intergovernmental Panel on Climate Change. This study updates our earlier calculations which showed that the observed global warming was predominantly human-caused. Two independent methods are used to analyze the temperature measurements: Singular Spectrum Analysis and Climate Model Simulation. The concurrence of the results of the two methods, each using 13 additional years of temperature measurements from 1998 through 2010, shows that it is humanity, not nature, that has increased the Earth’s global temperature since the 19th century. Humanity is also responsible for the most recent period of warming from 1976 to 2010. Internal climate variability is primarily responsible for the early 20th century warming from 1904 to 1944 and the subsequent cooling from 1944 to 1976. It is also found that the equilibrium climate sensitivity is on the low side of the range given in the IPCC Fourth Assessment Report.
文摘We apply Singular Spectrum Analysis to four datasets of observed global-mean near-surface temperature from start year to through 2012: HadCRU (to = 1850), NOAA (to = 1880), NASA (to = 1880), and JMA (to = 1891). For each dataset, SSA reveals a trend of increasing temperature and several quasi-periodic oscillations (QPOs). QPOs 1, 2 and 3 are predictable on a year-by-year basis by sine waves with periods/amplitudes of: 1) 62.4 years/0.11°C;2) 20.1 to 21.4 years/0.04°C to 0.05°C;and 3) 9.1 to 9.2 years/0.03°C to 0.04°C. The remainder of the natur°l variability is not predictable on a year-by-year basis. We represent this noise by its 90 percent confidence interval. We combine the predictable and unpredictable natural variability with the temperature changes caused by the 11-year solar cycle and humanity, the latter for both the Reference and Revised-Fair-Plan scenarios for future emissions of greenhouse gases. The resulting temperature departures show that we have moved from the first phase of learning—Ignorance—through the second phase—Uncertainty—and are now entering the third phase—Resolution—when the human-caused signal is much larger than the natural variability. Accordingly, it is now time to transition to the post-fossil-fuel age by phasing out fossil-fuel emissions from 2020 through 2100.
文摘The most recent US Congressional climate bill, H.R.5271 in 2014, proposes to reduce US emissions of carbon dioxide relative to their 2005 value by 80% in 2050. This bill does not provide a rationale for this rapid phase down of CO2 emissions. In 2012, we crafted a Fair Plan to Safeguard Earth’s Climate such that: 1) The cumulative trade-adjusted CO2 emissions by the developing countries equal the cumulative trade-adjusted CO2 emissions by the developed countries;2) The maximum global warming above preindustrial temperature does not exceed the 2°C (3.6°F) chosen by the United Nations Framework Convention on Climate Change “to prevent dangerous anthropogenic interference with the climate system”;and 3) The phase out of CO2 emissions begins as late as possible in the 21st century and proceeds at the slowest possible pace, consistent with objectives 1 and 2. The Fair Plan begins in 2020 and reduces the world’s emissions to zero in 2100. In the Fair Plan the emissions of the developed countries, including the United States, reach 80% below their 2005 values in 2094, that is, 44 years later than proposed by H.R.5271. While it is imperative that humanity begins to wean itself from fossil fuels no later than 2020, the transition from fossil to non-fossil energy need not be completed before 2100 if all countries follow their Fair Plan trajectories.
文摘Earth is the only habitable planet in the solar system and beyond in interstellar space for a distance that would take us at least 80,000 years to traverse at the speed of Voyager 1. Thus our home planet is “This Island Earth”. Here we use our Simple (engineering-type) Climate Model to calculate the change in global-mean near-surface air temperature from 1765 through the third millennium for historical emissions and two scenarios of future emissions of greenhouse gases: (1) a Reference scenario of unabated emissions, and (2) our Fair Plan scenario wherein emissions are phased out to zero from 2020 to 2100. The temperature change for the Reference cases increases to 5.2°C (9.4°F) in 2225 and remains there for at least 40 human generations. By design, the temperature change for the Fair Plan increases only to 2°C (3.6°F)—the limit adopted by the UN Framework Convention on Climate Change “to prevent dangerous anthropogenic interference with the climate system”—in 2082 and thereafter decreases through the remainder of the millennium. Accordingly, we need to adopt the Fair Plan to safeguard the climate of “This Island Earth”.
文摘Previously we have used Singular Spectrum Analysis (SSA) to deconstruct the global-mean near-surface temperature observations of the Hadley Centre—Climate Research Unit that extend from 1850 through 2012. While SSA is a very powerful tool, it is rather like a statistical “black box” that gives little intuition about its results. Accordingly, here we use the simplest statistical tool to provide such intuition, the Simple Moving Average (SMA). Firstly we use a 21-year SMA. This reveals a nonlinear trend and an oscillation of about 60 years' length. Secondly we use a 61-year SMA on the raw observations. This yields a nonlinear trend. We subtract this trend from the raw observations and apply a 21-year SMA. This yields a Quasi-periodic Oscillation (QPO) with a period and amplitude of about 62.4 years and 0.11°C. This is the QPO we discovered in our 1994 Nature paper, which has come to be called the Atlantic Multidecadal Oscillation. We then subtract QPO-1 from the detrended observations and apply an 11-year SMA. This yields QPO-2 with a period and amplitude of about 21.0 years and 0.04°C. We subtract QPO-2 from the detrended observations minus QPO-1 and apply a 3-year SMA. This yields QPO-3 with a period and amplitude of about 9.1 years and 0.03°C. QPOs 1, 2 and 3 are sufficiently regular in period and amplitude that we fit them by sine waves, thereby yielding the above periods and amplitudes. We then subtract QPO-3 from the detrended observations minus QPOs 1 and 2. The result is too irregular in period and amplitude to be fit by a sine wave. Accordingly we represent this unpredictable part of the temperature observations by a Gaussian probability distribution (GPD) with a mean of zero and standard deviation of 0.08°C. The sum of QPOs 1, 2 and 3 plus the GPD can be used to project the natural variability of the global-mean near-surface temperature to add to, and be compared with, the continuing temperature trend caused predominantly by humanity’s continuing combustion of fossil fuels.
文摘Earth’s climate future is in the hands of humanity. If emissions of greenhouse gases remain unabated, Earth’s climate will return to the climate of the Late Eocene, 35 million years ago, when sea level was 73 meters (240 feet) higher than today. Should that occur, many coastal cities around the world would be inundated. Moreover the Global Warming of this unabated Reference case will be comparable to the Global Warming from the Last Glacial Maximum 21,000 years ago to the beginning of the Holocene interglacial climate 11,000 years ago. However, this human-caused Global Warming would occur 50 times faster than that caused by nature. Alternatively, humanity can mitigate greenhouse-gas emissions to keep Global Warming below the 2°C maximum adopted by the United Nations Framework Convention on Climate Change “to prevent dangerous anthropogenic interference with the climate system”. This mitigation can either be done rapidly, as in the “80/50” Plan to reduce greenhouse-gas emissions 80% by 2050, or much more slowly, from 2020 to 2100, as in the Fair Plan to Safeguard Earth’s Climate. The Fair Plan is a compromise between doing nothing, as in the Reference case, and rapidly reducing greenhouse-gas emissions, as in the 80/50 Plan. Regardless of the Plan chosen to reduce greenhouse-gas emissions to keep Global Warming below the UNFCCC limit of 2°C (3.6°F), it should not be tantamount to our saying to one of our planetary spacecraft, Bon Voyage, call us when you get to your planetary destination. Rather, as with our spacecraft, the chosen climate-change policy should be monitored throughout the 21st century and Midcourse Corrections made thereto as needed to keep our “Climate Spacecraft” on track to achieve its “Climate Target”.
