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Significant anthropogenic-induced changes of climate classes since 1950.

Chan D, Wu Q - Sci Rep (2015)

Bottom Line: Here we examine changes in major Köppen climate classes from gridded observed data and their uncertainties due to internal climate variability using control simulations from Coupled Model Intercomparison Project 5 (CMIP5).About 5.7% of the global total land area has shifted toward warmer and drier climate types from 1950-2010, and significant changes include expansion of arid and high-latitude continental climate zones, shrinkage in polar and midlatitude continental climates, poleward shifts in temperate, continental and polar climates, and increasing average elevation of tropical and polar climates.Using CMIP5 multi-model averaged historical simulations forced by observed anthropogenic and natural, or natural only, forcing components, we find that these changes of climate types since 1950 cannot be explained as natural variations but are driven by anthropogenic factors.

View Article: PubMed Central - PubMed

Affiliation: School of Atmospheric Sciences, Nanjing University, 163 Xianlin Ave., Nanjing, Jiangsu, China, 210023.

ABSTRACT
Anthropogenic forcings have contributed to global and regional warming in the last few decades and likely affected terrestrial precipitation. Here we examine changes in major Köppen climate classes from gridded observed data and their uncertainties due to internal climate variability using control simulations from Coupled Model Intercomparison Project 5 (CMIP5). About 5.7% of the global total land area has shifted toward warmer and drier climate types from 1950-2010, and significant changes include expansion of arid and high-latitude continental climate zones, shrinkage in polar and midlatitude continental climates, poleward shifts in temperate, continental and polar climates, and increasing average elevation of tropical and polar climates. Using CMIP5 multi-model averaged historical simulations forced by observed anthropogenic and natural, or natural only, forcing components, we find that these changes of climate types since 1950 cannot be explained as natural variations but are driven by anthropogenic factors.

No MeSH data available.


Significant observed trends (black bars) marked with * in Fig. 2and the corresponding simulated trends of indices for 1950–1998; yellow, red and blue bars denote HIST-ALL, HIST-GHG and HIST-NAT runs, respectively. Each error bar at the left of an observed trend is the standard deviation (σ) of such trend estimated from 225 samples of 54-yr CMIP5 control runs and represents the natural variability of the observed or modeled trend. Simulated trends significantly different from the observation at the 5% level are marked with diamonds. The units are 2 × 105 m2 decade−1 for area, 10 km decade−1 for latitude and 5 m decade−1 for elevation indices.
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f3: Significant observed trends (black bars) marked with * in Fig. 2and the corresponding simulated trends of indices for 1950–1998; yellow, red and blue bars denote HIST-ALL, HIST-GHG and HIST-NAT runs, respectively. Each error bar at the left of an observed trend is the standard deviation (σ) of such trend estimated from 225 samples of 54-yr CMIP5 control runs and represents the natural variability of the observed or modeled trend. Simulated trends significantly different from the observation at the 5% level are marked with diamonds. The units are 2 × 105 m2 decade−1 for area, 10 km decade−1 for latitude and 5 m decade−1 for elevation indices.

Mentions: For significant trends in Fig. 2, Fig. 3 shows corresponding trends for HIST-ALL, HIST-GHG, and HIST-NAT multi-model averages. For each major climate type, the HIST-ALL and HIST-GHG experiments qualitatively reproduce all significant observed trends. A two-sided consistency test is conducted to determine whether the difference between the observed and any simulated trend is significantly different from zero at the 90% confidence level for each index of major climate type. The observed trends are consistent with those in the HIST-ALL run, except that the simulated B climate expansion is smaller than observed, which is explained by the finding that the models underestimate the observed precipitation trends826. By consistent, we mean that the observed trend lies within the 90% confidence interval obtained by combining the uncertainty for the ensemble-mean forced model trend with the uncertainty estimated from control runs. HIST-NAT trends are small and have the opposite sign of all significant observed trends. In Fig. 3, increases in well mixed greenhouse gases (based on HIST-GHG) are the main driver of significant changes in major climate types, but HIST-GHG runs overstate most trends because they omit offsetting cooling factors such as sulfate aerosols.


Significant anthropogenic-induced changes of climate classes since 1950.

Chan D, Wu Q - Sci Rep (2015)

Significant observed trends (black bars) marked with * in Fig. 2and the corresponding simulated trends of indices for 1950–1998; yellow, red and blue bars denote HIST-ALL, HIST-GHG and HIST-NAT runs, respectively. Each error bar at the left of an observed trend is the standard deviation (σ) of such trend estimated from 225 samples of 54-yr CMIP5 control runs and represents the natural variability of the observed or modeled trend. Simulated trends significantly different from the observation at the 5% level are marked with diamonds. The units are 2 × 105 m2 decade−1 for area, 10 km decade−1 for latitude and 5 m decade−1 for elevation indices.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4551970&req=5

f3: Significant observed trends (black bars) marked with * in Fig. 2and the corresponding simulated trends of indices for 1950–1998; yellow, red and blue bars denote HIST-ALL, HIST-GHG and HIST-NAT runs, respectively. Each error bar at the left of an observed trend is the standard deviation (σ) of such trend estimated from 225 samples of 54-yr CMIP5 control runs and represents the natural variability of the observed or modeled trend. Simulated trends significantly different from the observation at the 5% level are marked with diamonds. The units are 2 × 105 m2 decade−1 for area, 10 km decade−1 for latitude and 5 m decade−1 for elevation indices.
Mentions: For significant trends in Fig. 2, Fig. 3 shows corresponding trends for HIST-ALL, HIST-GHG, and HIST-NAT multi-model averages. For each major climate type, the HIST-ALL and HIST-GHG experiments qualitatively reproduce all significant observed trends. A two-sided consistency test is conducted to determine whether the difference between the observed and any simulated trend is significantly different from zero at the 90% confidence level for each index of major climate type. The observed trends are consistent with those in the HIST-ALL run, except that the simulated B climate expansion is smaller than observed, which is explained by the finding that the models underestimate the observed precipitation trends826. By consistent, we mean that the observed trend lies within the 90% confidence interval obtained by combining the uncertainty for the ensemble-mean forced model trend with the uncertainty estimated from control runs. HIST-NAT trends are small and have the opposite sign of all significant observed trends. In Fig. 3, increases in well mixed greenhouse gases (based on HIST-GHG) are the main driver of significant changes in major climate types, but HIST-GHG runs overstate most trends because they omit offsetting cooling factors such as sulfate aerosols.

Bottom Line: Here we examine changes in major Köppen climate classes from gridded observed data and their uncertainties due to internal climate variability using control simulations from Coupled Model Intercomparison Project 5 (CMIP5).About 5.7% of the global total land area has shifted toward warmer and drier climate types from 1950-2010, and significant changes include expansion of arid and high-latitude continental climate zones, shrinkage in polar and midlatitude continental climates, poleward shifts in temperate, continental and polar climates, and increasing average elevation of tropical and polar climates.Using CMIP5 multi-model averaged historical simulations forced by observed anthropogenic and natural, or natural only, forcing components, we find that these changes of climate types since 1950 cannot be explained as natural variations but are driven by anthropogenic factors.

View Article: PubMed Central - PubMed

Affiliation: School of Atmospheric Sciences, Nanjing University, 163 Xianlin Ave., Nanjing, Jiangsu, China, 210023.

ABSTRACT
Anthropogenic forcings have contributed to global and regional warming in the last few decades and likely affected terrestrial precipitation. Here we examine changes in major Köppen climate classes from gridded observed data and their uncertainties due to internal climate variability using control simulations from Coupled Model Intercomparison Project 5 (CMIP5). About 5.7% of the global total land area has shifted toward warmer and drier climate types from 1950-2010, and significant changes include expansion of arid and high-latitude continental climate zones, shrinkage in polar and midlatitude continental climates, poleward shifts in temperate, continental and polar climates, and increasing average elevation of tropical and polar climates. Using CMIP5 multi-model averaged historical simulations forced by observed anthropogenic and natural, or natural only, forcing components, we find that these changes of climate types since 1950 cannot be explained as natural variations but are driven by anthropogenic factors.

No MeSH data available.