|Title||Global and regional importance of the direct dust-climate feedback|
|Publication Type||Journal Article|
|Year of Publication||2018|
|Authors||Kok J.F, Ward D.S, Mahowald N.M, Evan AT|
|Type of Article||Article|
|Keywords||aerosols; african dust; atlantic; climate; cycle; earth system model; emission model; general-circulation model; land-use; Science & Technology - Other Topics; size distribution; tropical|
Feedbacks between the global dust cycle and the climate system might have amplified past climate changes. Yet, it remains unclear what role the dust-climate feedback will play in future anthropogenic climate change. Here, we estimate the direct dust-climate feedback, arising from changes in the dust direct radiative effect (DRE), using a simple theoretical framework that combines constraints on the dust DRE with a series of climate model results. We find that the direct dust-climate feedback is likely in the range of -0.04 to +0.02Wm(-2) K-1, such that it could account for a substantial fraction of the total aerosol feedbacks in the climate system. On a regional scale, the direct dust-climate feedback is enhanced by approximately an order of magnitude close to major source regions. This suggests that it could play an important role in shaping the future climates of Northern Africa, the Sahel, the Mediterranean region, the Middle East, and Central Asia.
|Short Title||Nat. Commun.|
Our results indicate that the sign and magnitude of the direct dust–climate feedback varies greatly on regional scales. This occurs in part because of large spatial variability in dust loading, and in part because the global dust DRE is the sum of counteracting cooling and warming effects that are both modulated by a variety of factors. Dust cooling effects arise from scattering of SW radiation, which dominates for fine dust and is enhanced over dark surfaces. In contrast, dust warming effects arise from scattering of LW radiation and absorption of SW and LW radiation. These warming effects dominate for coarse dust and are enhanced over bright surfaces and for high altitude dust layers. The dependence of the radiative effects on particle size causes the fining of the dust size distribution during long-range transport to produce a gradual shift from warming interactions to cooling interactions. However, this effect is often overwhelmed by the coincident shift from high albedo deserts close to source regions to low albedo ocean and vegetated surfaces further from source regions.