Summary for policymakers Technical summary 1. The climate system - an overview 2. Observed climate variability and change 3. The carbon cycle and atmospheric CO2 4. Atmospheric chemistry and greenhouse gases 5. Aerosols, their direct and indirect effects 6. Radiative forcing of climate change 7. Physical climate processes and feedbacks 8. Model evaluation 9. Projections of future climate change 10. Regional climate simulation - evaluation and projections 11. Changes in sea level 12. Detection of climate change and attribution of causes 13. Climate scenario development 14. Advancing our understanding Glossary Index Appendix.

Climate change 2001: the scientific basis

The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth system. Here, we revise and update the planetary boundary framework, with a focus on the underpinning biophysical science, based on targeted input from expert research communities and on more general scientific advances over the past 5 years. Several of the boundaries now have a two-tier approach, reflecting the importance of cross-scale interactions and the regional-level heterogeneity of the processes that underpin the boundaries. Two core boundaries—climate change and biosphere integrity—have been identified, each of which has the potential on its own to drive the Earth system into a new state should they be substantially and persistently transgressed.

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Planetary boundaries: Guiding human development on a changing planet

Changes in Atmospheric Constituents and in Radiative Forcing

Black carbon aerosol plays a unique and important role in Earth's climate system. Black carbon is a type of carbonaceous material with a unique combination of physical properties. This assessment provides an evaluation of black-carbon climate forcing that is comprehensive in its inclusion of all known and relevant processes and that is quantitative in providing best estimates and uncertainties of the main forcing terms: direct solar absorption; influence on liquid, mixed phase, and ice clouds; and deposition on snow and ice. These effects are calculated with climate models, but when possible, they are evaluated with both microphysical measurements and field observations. Predominant sources are combustion related, namely, fossil fuels for transportation, solid fuels for industrial and residential uses, and open burning of biomass. Total global emissions of black carbon using bottom-up inventory methods are 7500 Gg yr−1 in the year 2000 with an uncertainty range of 2000 to 29000. However, global atmospheric absorption attributable to black carbon is too low in many models and should be increased by a factor of almost 3. After this scaling, the best estimate for the industrial-era (1750 to 2005) direct radiative forcing of atmospheric black carbon is +0.71 W m−2 with 90% uncertainty bounds of (+0.08, +1.27) W m−2. Total direct forcing by all black carbon sources, without subtracting the preindustrial background, is estimated as +0.88 (+0.17, +1.48) W m−2. Direct radiative forcing alone does not capture important rapid adjustment mechanisms. A framework is described and used for quantifying climate forcings, including rapid adjustments. The best estimate of industrial-era climate forcing of black carbon through all forcing mechanisms, including clouds and cryosphere forcing, is +1.1 W m−2 with 90% uncertainty bounds of +0.17 to +2.1 W m−2. Thus, there is a very high probability that black carbon emissions, independent of co-emitted species, have a positive forcing and warm the climate. We estimate that black carbon, with a total climate forcing of +1.1 W m−2, is the second most important human emission in terms of its climate forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. Sources that emit black carbon also emit other short-lived species that may either cool or warm climate. Climate forcings from co-emitted species are estimated and used in the framework described herein. When the principal effects of short-lived co-emissions, including cooling agents such as sulfur dioxide, are included in net forcing, energy-related sources (fossil fuel and biofuel) have an industrial-era climate forcing of +0.22 (−0.50 to +1.08) W m−2 during the first year after emission. For a few of these sources, such as diesel engines and possibly residential biofuels, warming is strong enough that eliminating all short-lived emissions from these sources would reduce net climate forcing (i.e., produce cooling). When open burning emissions, which emit high levels of organic matter, are included in the total, the best estimate of net industrial-era climate forcing by all short-lived species from black-carbon-rich sources becomes slightly negative (−0.06 W m−2 with 90% uncertainty bounds of −1.45 to +1.29 W m−2). The uncertainties in net climate forcing from black-carbon-rich sources are substantial, largely due to lack of knowledge about cloud interactions with both black carbon and co-emitted organic carbon. In prioritizing potential black-carbon mitigation actions, non-science factors, such as technical feasibility, costs, policy design, and implementation feasibility play important roles. The major sources of black carbon are presently in different stages with regard to the feasibility for near-term mitigation. This assessment, by evaluating the large number and complexity of the associated physical and radiative processes in black-carbon climate forcing, sets a baseline from which to improve future climate forcing estimates.

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Bounding the role of black carbon in the climate system: A scientific assessment

Human activities are releasing tiny particles (aerosols) into the atmosphere. These human-made aerosols enhance scattering and absorption of solar radiation. They also produce brighter clouds that are less efficient at releasing precipitation. These in turn lead to large reductions in the amount of solar irradiance reaching Earth's surface, a corresponding increase in solar heating of the atmosphere, changes in the atmospheric temperature structure, suppression of rainfall, and less efficient removal of pollutants. These aerosol effects can lead to a weaker hydrological cycle, which connects directly to availability and quality of fresh water, a major environmental issue of the 21st century.

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Aerosols, climate, and the hydrological cycle

Extensive measurements of columnar aerosol optical
depth (AOD), composite (M T ) and black carbon aerosol
mass (M B ) concentrations were made over the
tropical Indian and Southern Oceans as a part of the
Pilot Expedition to the Southern Ocean during the
boreal winter The AOD, M T and M B show large latitudinal
gradient towards south up to ITCZ Beyond
ITCZ, up to 56°S, AOD and M B show very low and
steady values However MT shows large variations in
the Southern Ocean due to the enhanced production
of sea salt aerosols associated with high sea surface
winds The short wave aerosol radiative forcing at the
surface over north of equator is in the range – 10 to
– 23 W m –2 , whereas that over the Southern Ocean
was in the range – 4 to – 5 W m –2  The corresponding
atmospheric forcing was in the range of 6–13 W m –2 and
08–14 W m –2  This large north–south change in the
aerosol radiative forcing has important implications
to the meridional circulation and hence to climate

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Latitudinal gradient in aerosol properties over the Indian and Southern Oceans during the austral summer

The commercially valuable and nutritionally enriched fruits of Palmyra palm (Borassus flabellifer) have many health benefits, and also they are considered as a source for medicines. In the current research, the bioactivity (antibacterial and antiadhesion) of the fruit husk extract of Palmyra palm was tested against biofilm-forming bacteria Alteromonas sp and Pseudomonas sp. In addition, an antifouling coat was prepared by incorporating the Palmyra palm fruit husk extract into epoxy resin and its antifouling property was evaluated against marine biofoulers. The obtained results indicated that the Palmyra palm fruit husk extract has the potential to inhibit the settlement of marine microfoulers (bacteria and microalgae) and macrofoulers (barnacles and tubeworms). The bioactive fraction of Palmyra palm fruit husk extracts isolated using thin-layer chromatography revealed the presence of 15 compounds including the groups of fatty acids, ketones, and cyanides in the GC–MS analysis. According to the findings of the present study, Palmyra palm fruit husk could be used as the source for the isolation of an effective eco-friendly antifouling agent.

Antifouling Potential of Palmyra Palm ( Borassus flabellifer ) Fruit Husk Extract

Propagation through turbulent media produces complex amplitude fluctuations and temporal spreading of narrow optical pulses. Light-absorbing aerosols present in the atmospheric transmission path will perturb the refractive index structure parameter (Cn2) through atmospheric heating. The consequent enhancement in broadening and attenuation of ultrashort (femtosecond) optical pulses has been calculated by combining multi-satellite observations, radiosonde profiles and computational radiative transfer. It is shown that narrower optical pulses are more vulnerable to aerosol-induced impairments while broader pulses are more resilient, notwithstanding three to four orders of enhanced optical scintillation.

Enhanced optical pulse broadening in free-space optical links due to the radiative effects of atmospheric aerosols.

Under ISRO-GBP land campaign-I, the concentrations of CO and SO2 gases were simultaneously measured during 1-29 Feb. 2004 over southern India. These measurements were made onboard instrument vehicle along the road network during the dry, winter season of 2004. The study region covered coastal, industrial, urban, rural, remote, semi-arid and vegetated forest lands in the central part of the southern India. Average CO concentration at Nellore, an urban and coastal site is comparatively high (1300 ppbv) and the same is low (620 ppbv) at Sri Perumbuthur, a semi-urban site. These maximum levels of CO at Nellore may be due to traffic emissions and shallow surface layer. Average SO2 concentrations at Sri Perumbuthur and Shadnagar (5 ppbv) are significantly higher than those at other locations. Fairly good correlation has been established between CO, SO2 and meteorological parameters over the study region.

http://nopr.niscair.res.in/bitstream/123456789/4723/1/IJRSP%2037%283%29%20216-220.pdf

Measurement of CO and SO 2 trace gases in southern India during ISRO-GBP Land Campaign - I

The extracellular polymeric substance (EPS) produced by an epibiotic bacterium isolated from the surface of the polychaete worm Platynereis dumerilii was assessed for its inhibitory activity against two biofilm forming bacterial strains. The polychaete Platynereis dumerilii was collected from the coastal waters and the bacterial communities associated with the surface was isolated using traditional culture method. The EPS of the bacterial strain strongly inhibited the growth of target bacteria in disc diffusion assay. The adhesion assay showed that the number of cells adhered on the control slides were higher than that the number of cells found on the slides coated with EPS. The bacterial strain was identified as Exiguobacterium sp. by 16S rRNA gene sequencing. Thin layer chromatography analysis showed the presence of a single active compound in the EPS with the Rf value of 1.47 cm. The HPLC spectrum of the EPS showed two prominent peaks. Results indicate that epibiotic bacterial communities associated with polychaetes would serves as a potential source for the biofilm inhibitory compounds.

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Biofilm inhibitory activity of extracellular polymeric substance produced by "Exiguobacterium sp." associated with the polychaete "Platynereis dumerilii"

Sathianeson Satheesh

Papers

Latitudinal gradient in aerosol properties over the Indian and Southern Oceans during the austral summer

Antifouling Potential of Palmyra Palm ( Borassus flabellifer ) Fruit Husk Extract

Enhanced optical pulse broadening in free-space optical links due to the radiative effects of atmospheric aerosols.

Measurement of CO and SO 2 trace gases in southern India during ISRO-GBP Land Campaign - I

Biofilm inhibitory activity of extracellular polymeric substance produced by "Exiguobacterium sp." associated with the polychaete "Platynereis dumerilii"