President Dilma Rousseff is facing one of the defining moments of her presidency as pressure builds on her to veto a bill that would open vast protected areas of forests to ranching and farming, potentially reversing Brazil’s major gains in slowing Amazon deforestation.

The Amazon is a globally important system, providing a host of ecosystem services from climate regulation to food sources. It is also home to a quarter of all global diversity. Large swathes of forest are removed each year, and many models have attempted to predict the spatial patterns of this forest loss. The spatial patterns of deforestation are determined largely by the patterns of roads that open access to frontier areas and expansion of the road network in the Amazon is largely determined by profit seeking logging activities.

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.

The sound of chainsaws in the Amazon rainforest has faded in recent years as deforestation has slowed, last year dropping to less than one-third of its long-term average. But last week, the lower house of Brazil’s
National Congress passed a bill that observers say could drastically reduce forest protection.

Peru became the latest developing country to enact a domestic climate change initiative in the absence of a binding global pact, adopting a resolution on Thursday to lower carbon emissions in its fast-growing economy.

As one of the world's most geographically diverse places, Peru said it is already feeling the effects of a changing climate, such as melting tropical glaciers in the Andes and high levels of solar radiation.

The nature and scale of pre-Columbian land use and the consequences of the 1492 “Columbian Encounter” (CE) on Amazonia are among the more debated topics in New World archaeology and paleoecology. However, pre-Columbian human impact in Amazonian savannas remains poorly understood. Most paleoecological studies have been conducted in neotropical forest contexts. Of studies done in Amazonian savannas, none has the temporal resolution needed to detect changes induced by either climate or humans before and after A.D. 1492, and only a few closely integrate paleoecological and archaeological data.

Due to rising energy demands and abundant untapped potential, hydropower projects are rapidly increasing in the Neotropics. This is especially true in the wet and rugged Andean Amazon, where regional governments are prioritizing new hydroelectric dams as the centerpiece of long-term energy plans. However, the current planning for hydropower lacks adequate regional and basin-scale assessment of potential ecological impacts.

Tropical forests in Africa may be more resilient to future climate change than the Amazon and other regions, a gathering of scientists has said. An international conference agreed that the region’s surviving tree species had endured a number of climatic catastrophes over the past 4,000 years.

As a result, they are better suited to cope with future shifts in the climate.

The event at the University of Oxford looked at the “fate of Africa’s tropical forests in the 21st century”.

President Evo Morales said Tuesday that he was rescinding a contract awarded to the Brazilian company OAS to build a road through the Amazon, casting further doubt on a project that set off fierce antigovernment protests last year. Mr. Morales partly halted work on the most controversial stretch of the road in September, seeking to ease tensions over the $415 million project, which met with strong opposition from his indigenous base. Brazil’s state development bank was to have financed about 80 percent of the project, which has been at the center of Bolivian politics for nearly a year. Mr.

The world is close to reaching tipping points that will make it irreversibly hotter, making this decade critical in efforts to contain global warming, scientists warned on Monday.

Scientific estimates differ but the world's temperature looks set to rise by six degrees Celsius by 2100 if greenhouse gas emissions are allowed to rise uncontrollably.

As emissions grow, scientists say the world is close to reaching thresholds beyond which the effects on the global climate will be irreversible, such as the melting of polar ice sheets and loss of rainforests.

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