The magnitude and evolution of parameters that characterize feedbacks in the coupled carbon–climate system are compared across nine Earth system models (ESMs). The analysis is based on results from biogeochemically, radiatively, and fully coupled simulations in which CO2 increases at a rate of 1% yr−1. These simulations are part of phase 5 of the Coupled Model Intercomparison Project (CMIP5). The CO2 fluxes between the atmosphere and underlying land and ocean respond to changes in atmospheric CO2 concentration and to changes in temperature and other climate variables. The carbon–concentration and carbon–climate feedback parameters characterize the response of the CO2 flux between the atmosphere and the underlying surface to these changes. Feedback parameters are calculated using two different approaches. The two approaches are equivalent and either may be used to calculate the contribution of the feedback terms to diagnosed cumulative emissions. The contribution of carbon–concentration feedback to...

Carbon-concentration and carbon-climate feedbacks in CMIP5 Earth system models

Effects Of Climate Change

Climate change is altering the seasonal distribution, interannual variability and overall magnitude of precipitation. A new global measure of precipitation seasonality is proposed, and application of this method to observations from the tropics shows that increases in variability were accompanied by shifts in seasonal magnitude, timing and duration.

Changes in rainfall seasonality in the tropics

Climate change will increase the recurrence of extreme weather events such as drought and heavy rainfall. Evidence suggests that modifications in extreme weather events pose stronger threats to ecosystem functioning than global trends and shifts in average conditions. As ecosystem functioning is connected with ecological services, this has far-reaching effects on societies in the 21st century. Here, we: (i) present the rationale for the increasing frequency and magnitude of extreme weather events in the near future; (ii) discuss recent findings on meteorological extremes and summarize their effects on ecosystems and (iii) identify gaps in current ecological climate change research.

Iconographies supplémentaires de l'article : Research frontiers in climate change: Effects of extreme meteorological events on ecosystems

An urgent need for sustainable thinking in agriculture – An Indian scenario

Tropical soils are nutrient limited and are markedly influenced by seasonality. The seasonal precipitation affects soil wet-dry cycle and has significant consequences for ecosystem functioning and processes. It has been predicted that in tropical countries, a substantial change will occur in the annual mean temperature and precipitation regimes in the future. However, we have little knowledge as to how the soil properties and processes will change with the change in the climatic conditions in tropics. In this chapter, we have tried to collate studies related to the effect of changing climatic condition (temperature and precipitation) on the soil in the tropics. The change in precipitation, than temperature, has more impact on the ecosystem processes in the tropics. Within the tropics the moist and dry ecosystems respond differently to the change in precipitation. Perhaps experimental studies using rain-out shelters may provide more precise information on the effect of the changing pattern of precipitation and drought on the health and vigour of tropical soils. There is a conspicuous lack of literature on the effect of temperature on tropical soils; for getting a complete picture and more precise information, we need more focused studies related to climate change in the tropical region.

Influence of Changing Patterns of Precipitation and Temperature on Tropical Soil Ecosystem

Hyptis suaveolens is considered one of the most potent invaders in the eastern part of Uttar Pradesh, India. Climate change especially precipitation variability along with invasion has enormous consequences. To understand how an invasive plant (H. suaveolens) performs and interacts with precipitation variability, particularly in tropical monsoon climate, is vital. To assess the above, three rainout shelters with simulated rainfall of 1600 mm (60% more rainfall than ambient), 1100 mm (average rainfall) and 800 mm (20% less rainfall than ambient) along with one unsheltered plot (open C) were established. Three invaded grassland (IG) and three uninvaded grasslands (NIG) patches of 1 × 1 m2 size were established randomly in each sheltered and unsheltered plot. Among the studied physiological properties and growth measurements, photosynthetic rate, height, diameter and biomass varied significantly with precipitation, in general, the maximum value of these in plots receiving maximum precipitation. Also, the aboveground biomass of H. suaveolens was found to be more sensitive towards precipitation treatment than belowground biomass. H. suaveolens biomass was linearly related to soil moisture (R2 = 0.73), and a linear combination of SM and soil pH increased the R2 value by 19%. The results indicate that H. suaveolens mediates certain soil properties especially related to N-mineralisation, to maintain a constant supply of nutrient, for faster growth under the favourable condition of enhanced precipitation. These findings suggest that the population of H. suaveolens has not evolved drought tolerance, so it is likely that H. suaveolens will not spread in the part of the world which is drier either naturally or due to climate change.

Impact of rainfall variability on the ecophysiology of Hyptis suaveolens : a study in the constructed tropical grassland

Nowadays soil respiration has become an important issue in research. Measurement of soil respiration helps in determining the carbon budget under the influence of global climate change. Rainfall variability and nitrogen (N) input both have a profound impact on soil respiration and its components, i.e. autotrophic and heterotrophic respiration. Besides, soil respiration also shows considerable change due to global warming. According to emissions scenario, the elevated CO2 concentration would increase the soil surface temperature by 2oC in the coming 35 years which may lead to huge C-losses to the atmosphere. Such carbon losses to the atmosphere would aggravate the effects of global warming on the human race. Although some progress had been made in soil respiration research about rainfall variability and N-input, there are discrepancies in the results. But despite considerable scientific attention in recent years, there is no consensus on the direction and magnitude of warming-induced changes in soil carbon. Soil respiration changes with climate but to confirm it observationally have big constraints such as high spatial variability in soil respiration, inaccessibility of the soil medium and inability of the instruments to measure soil respiration on large scales. Further, most of the soil respiration studies about rainfall variability and N-input have been conducted in temperate regions, and tropics have remained ignored. Though tropical countries have not yet experienced the extreme variations in rainfall, still under the ongoing climate change the tropical region would also start to experience altered rainfall regimes. Rainfall variability and N-input are the consequences of intense global climate change and industrialisation, respectively. There are reports from grasslands that the antecedent soil moisture determines the strength of the effect of rainfall on soil respiration. N-input is reported to increase soil respiration only when water addition accompanied it. Further, the effect of N-input on soil respiration was different for the short term and long term addition of nitrogen. Likewise many ecosystem warming experiments suggest that warming increases the carbon fluxes to and from the soil, but the net global balance between these responses is uncertain.

Effect of Precipitation and Nitrogen Input on Soil Respiration in Grasslands

Invasive alien plant species (IAPS) are considered to be an important driver of global change in biodiversity, community structure, and ecosystem processes of the invaded ecosystem, fundamental to human well-being (access to secure livelihoods, health, good social relations, security and freedom). There isa lack of studies on IAPS, concerning its economic quantification, livelihood considerations and human health risk assessments. In this article, we review the role of invasive alien plant species in modulating native plant species diversity, environment, ecosystem, climate change, land-use change, socio-economic security and also tried to discuss the role of IAPS on the health of humans and human well-being. We suggest some management practices and use of advance tools such as remote sensing and GIS to assess, map and monitor the vulnerability of IAPS. These advance technologies may also help in the detection of impact of IAPS on ecosystems, and its conservation and restoration.

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Assessing the impact of invasive alien plant species on environment, ecosystem services and human health

Warmer climate or tropical agriculture is already at its ecological maxima and is more vulnerable to climate change. Increase in temperature and intermittent drought in growing season, which is of due to weaken monsoonal circulation, will have devastating effect on agriculture productivity. The study reported that the productivity of tropical agriculture will be reduced due to climate change by 2100. Research related to climate change in tropics showed an increase in temperature and decrease in rainfall. Thus, the conservation of tropical agriculture is becoming imperative to have a continuous supply of food for the evergrowing population. In this chapter, we are discussing the conservation practices such as the use of improved variety of crops and livestock; change in cropping system (agroforestry), water conservation practices (drip irrigation, ground and surface water recharge), etc., to achieve the goal of sustainable agriculture. Further, we have also suggested climate-smart agriculture practices as they help in the mitigation of greenhouse gasses (GHGs) emission and other pollutants which deteriorate the environment vigorously.

Talat Afreen

Papers

Influence of Changing Patterns of Precipitation and Temperature on Tropical Soil Ecosystem

Impact of rainfall variability on the ecophysiology of Hyptis suaveolens : a study in the constructed tropical grassland

Effect of Precipitation and Nitrogen Input on Soil Respiration in Grasslands

Assessing the impact of invasive alien plant species on environment, ecosystem services and human health

Conservation of Tropical Agriculture in the Era of Changing Climate