This article first appeared on guardian. Email Tweet Share. Vicious circle Efforts to boost agricultural production often lead to deforestation, a major contributor to global greenhouse gas emissions. Meet the people trying to help. Animals Whales eat three times more than previously thought. Environment Planet Possible India bets its energy future on solar—in ways both small and big. Environment As the EU targets emissions cuts, this country has a coal problem. Paid Content How Hong Kong protects its sea sanctuaries.
History Magazine These 3,year-old giants watched over the cemeteries of Sardinia. Magazine How one image captures 21 hours of a volcanic eruption. Science Why it's so hard to treat pain in infants. Science The controversial sale of 'Big John,' the world's largest Triceratops.
Science Coronavirus Coverage How antivirals may change the course of the pandemic. Science Coronavirus Coverage U. Travel A road trip in Burgundy reveals far more than fine wine. Travel My Hometown In L. Travel The last artists crafting a Thai royal treasure.
Subscriber Exclusive Content. Their marginalization leads to reduced human security and increased vulnerability to factors of change, like drought C Regional and Global Consequences of Desertification beyond Drylands.
Desertification has environmental impacts at the global and regional scale. Affected areas may sometimes be located thousands of kilometers away from the desertified areas. Desertification-related processes such as reduction of vegetation cover, for instance, increase the formation of aerosols and dust. These, in turn, affect cloud formation and rainfall patterns, the global carbon cycle, and plant and animal biodiversity. For example, visibility in Beijing is often adversely affected by dust storms originating in the Gobi Desert in springtime.
Large dust storms emanating from China affect the Korean peninsula and Japan and are observed to even have an impact on North American air quality. An increase in desertification -related dust storms is widely considered to be a cause of ill health fever, coughing, and sore eyes during the dry season. Dust emanating from the East Asian region and the Sahara has also been implicated in respiratory problems as far away as North America and has affected coral reefs in the Caribbean.
Dust storms can also have positive impacts, however; for example, air-transported dust deposits from Africa are thought to improve soil quality in the Americas. The societal and political impacts of desertification also extend to non-dryland areas. Droughts and loss of land productivity are predominant factors in movement of people from drylands to other areas, for example medium certainty. As the report puts it:.
A single global map of land degradation cannot satisfy all views or needs. The parts of the world with the most potential issues shown by orange and red shading — such as India, Pakistan, Zimbabwe and Mexico — are thus identified as particularly at risk from degradation.
Shading indicates the number of coincident risks. The areas with the fewest are shown in blue, which then increase through green, yellow, orange and the most in red. Credit: Publication Office of the European Union. As desertification cannot be characterised by a single metric, it is also tricky to make projections for how rates of degradation could change in the future.
In addition, there are numerous socio-economic drivers that will contribute. For example, the number of people directly affected by desertification is likely to increase purely because of population growth.
The impact of climate change on aridity is also complicated. A warmer climate is generally more able to evaporate moisture from the land surface — potentially increasing dryness in combination with hotter temperatures. These policies include a shift to low-carbon energy technologies and the deployment of carbon capture and storage. In RCP4. By , global temperatures are likely to rise by C above pre-industrial levels. However, climate change will also affect rainfall patterns, and a warmer atmosphere can hold more water vapour, potentially increasing both average and heavy rainfall in some areas.
There is also a conceptual question of distinguishing long-term changes in the dryness of an area with the relatively short-term nature of droughts. In general, the global area of drylands is expected to expand as the climate warms. Projections under the RCP4.
Research also shows that climate change is already increasing both the likelihood and severity of droughts around the world. This trend is likely to continue. The likely range of global temperatures by for RCP8. However, it should be noted that not all drylands are expected to get more arid with climate change.
The map below, for example, shows the projected change for a measure of aridity defined as the ratio of rainfall to potential evapotranspiration , PET by under climate model simulations for RCP8. The areas shaded red are those expected to become drier — because PET will increase more than rainfall — while those in green are expected to become wetter. The latter includes much of the Sahel and East Africa, as well as India and parts of northern and western China.
Reproduced with permission from Steven Sherwood. Climate model simulations also suggest that rainfall, when it does occur, will be more intense for almost the entire world , potentially increasing the risks of soil erosion.
Limiting global warming is therefore one of the key ways to help put a break on desertification in future, but what other solutions exist? What is very clear is that prevention is better — and much cheaper — than cure. Even small scale land mismanagement can lead to degradation at larger scales, so the problem is quite complex and hard to manage.
The idea of LDN, explained in detail in the video below, is a hierarchy of responses: first to avoid land degradation, second to minimise it where it does occur, and thirdly to offset any new degradation by restoring and rehabilitating land elsewhere. The outcome being that overall degradation comes into balance — where any new degradation is compensated with reversal of previous degradation.
SLM essentially means maximising the economic and social benefits of the land while also maintaining and enhancing its productivity and environmental functions. This can comprise a whole range of techniques, such as rotational grazing of livestock, boosting soil nutrients by leaving crop residues on the land after harvest, trapping sediment and nutrients that would otherwise be lost through erosion, and planting fast-growing trees to provide shelter from the wind.
0コメント