The rate of global mean surface temperature (GMST) warming has slowed this century despite the increasing concentrations of greenhouse gases. Climate model experiments show that this slowdown was largely driven by a negative phase of the Pacific Decadal Oscillation (PDO), with a smaller external contribution from solar variability, and volcanic and anthropogenic aerosols . The prevailing view is that this negative PDO occurred through internal variability.

We present the measurements of cloud-base height variations over ARIES, Nainital (79.45°E, 29.37°N, 1958 m amsl) obtained from Vaisala Ceilometer, during the nearly year-long Ganges Valley Aerosol Experiment (GVAX).

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In this paper, we evaluate the performance of the chemical transport model ‘CHIMERE’ over large Indian region (4–37.5°N; 67–88.5°E) for multiple years (2006, 2007 and 2008) by comparing the model simulations with concurrent aerosol measurements from different locations. Model simulated nearsurface black carbon mass concentrations agreed satisfactorily with measurements at various locations (oceanic, inland and island sites), in general, except during monsoon months, when the model underpredicted the measurements.

In order to understand the regional climate implications of aerosols over Indo Gangetic Plains (IGP), a major Indo-US field experiment, Ganges Valley Aerosol Experiment (GVAX) was conducted during 2011– 12. Atmospheric Radiation Measurement (ARM) mobile facility (AMF) was deployed at the northern Indo-Gangetic Plain over the high-altitude site, Manora Peak, Nainital (29°21′33.84″N, 79°27′29.27″E, 1980 m amsl) in Central Himalayas, for an year-round measurement of aerosols, clouds and other climate-relevant atmospheric parameters.

Worldwide heavy oil and bitumen deposits amount to 9 trillion barrels of oil distributed in over 280 basins around the world, with Canada home to oil sands deposits of 1.7 trillion barrels. The global development of this resource and the increase in oil production from oil sands has caused environmental concerns over the presence of toxic compounds in nearby ecosystems and acid deposition. The contribution of oil sands exploration to secondary organic aerosol formation, an important component of atmospheric particulate matter that affects air quality and climate, remains poorly understood.

On his late-night talk show, Jimmy Kimmel recently invited climate scientists to explain that they’re not just messing with us about global warming.

Widespread haze layers usually cover China like low clouds, exerting marked influence on air quality and regional climate. With recent Collection 6 MODIS Deep Blue aerosol data in 2000–2015, we analyzed the trends of regional haze pollution and the corresponding influence of atmospheric circulation in China.

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About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across.

Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded.

OTTAWA — The amount of pollution created by vapor from Canada’s oil sands, which contributes to climate change, ranks on par with most major cities in North America, according to a new study by the

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