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Short-lived climate pollutants (SLCPs) including methane, tropospheric ozone, and black carbon in this work, is a set of compounds with shorter lifetimes than carbon dioxide (CO2) and can cause warming effect on climate. Here, the effective radiative forcing (ERF) is estimated by using an online aerosol-climate model (BCC_AGCM2.0_CUACE/Aero); then the climate responses to SLCPs concentration changes from the pre-industrial era to the present (1850-2010) are estimated. The global annual mean ERF of SLCPs was estimated to be 0.99 [0.79-1.20] W m(-2), and led to warming effects over most parts of the globe, with the warming center (about 1.0 K increase) being located in the mid-high latitudes of the Northern Hemisphere (NH) and the ocean around Antarctica. The changes in annual mean surface air temperature (SAT) caused by SLCPs changes were more prominent in the NH [0.78 (0.62-0.94) K] than in the Southern Hemisphere [0.62 (0.45-0.74) K], and the global annual mean value is 0.70 K. By looking at other variable responses, we found that precipitation had been increased by about 0.10 mm d(-1) in mid- and high-latitudes and decreased by about 0.20 mm d(-1) in subtropical regions, with the global annual mean value of 0.02 mm d(-1). Changes in SLCPs also influenced atmospheric circulation change, a northward shift in the Intertropical Convergence Zone was induced due to the interhemispheric asymmetry in SAT. However, it is found in this work that SLCPs changes had little effect on global average cloud cover, whereas the local cloud cover changes could not be ignored, low cloud cover increase by about 2.5% over high latitudes in the NH and the ribbon area near 60 degrees S, and high cloud cover increased by more than 2.0% over northern Africa and the Indian Ocean. Finally, we compared the ERFs and global and regional warming effects of SLCPs with those induced by CO2 changes. From 1850 to the present, the ERF of SLCPs was equivalent to 66%, 83%, and 50% of that of CO2 in global, NH, and SH mean, respectively. The increases in SAT caused by SLCPs were 43% and 55% of those by CO2 over the globe and China, respectively.

期刊论文 2022-09-27 DOI: 10.3389/feart.2022.1008164

The boreal forest accounts for approximately 22% of the Northern Hemisphere landmass with nearly 40% of this huge biome growing on continuously frozen soils. Projected climate change leading to degradation of permafrost and increasing drought situation at high latitudes in Eurasia will seriously affect productivity of forests on permafrost. Here we present the results of an on-going research of tree radial growth in the midst of the permafrost zone in Siberia, Russia (Tura region, 64 degrees N, 100 degrees E, 140-610 m a.s.1.). Tree-ring width and density chronologies of Gmelin larch and Siberian spruce from a great variety of sites characterized by different thermo-hydrological regime of soils are analyzed. The obtained results reveal that current tree radial growth and tree-ring structure in permafrost region in Siberia are largely dependent on local site conditions and may be constrained by low air and soil temperatures as well as soil water availability. Varying climatic responses and seasonal radial growth of trees at different habitats indicate a range of possible scenarios of further development of northern larch stands. Forest fire is another important factor strongly affecting tree stand dynamics and forest ecosystem functioning in the continuous permafrost zone. Analysis of tree-ring parameters indicate that post-fire dynamics of tree-ring structure is in accordance with the changes in habitat conditions caused by removal by fire and then gradual recovery of ground vegetation resulting in an alteration in soil active layer depth. In general, the results of this multi-proxy analysis for trees growing under various conditions in the continuous permafrost zone in Siberia allow assumptions about changes in tree productivity, stand dynamics and therefore carbon uptake under projected climate change and permafrost degradation.

期刊论文 2016-01-01 ISSN: 1314-2704
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