Climate Change Risks in Brazil

The risks of global climate change go from high to very high with an average increase in temperature of 4 °C or more. This includes serious and generalised impacts related to the extinction of endangered species, great risks to global and regional food security, in addition to climate risks associated to alterations in extreme events like heat waves, extreme rainfall and coastal flooding, which are already moderate to high with 1 °C increase in temperature. The consequences of a dangerous climate change due to 4 °C or above warming are suggested to be devastating: the inundation of coastal cities; increasing risks for food production potentially leading to higher malnutrition rates; many dry regions becoming dryer, wet regions, wetter; unprecedented heat waves in many regions, especially in the tropics; substantially exacerbated water scarcity and drought in many regions; increased frequency of high-intensity tropical cyclones; and irreversible loss of biodiversity, including coral reef systems (World Bank, 2012).

This chapter considers four emission scenarios of CMIP5 simulations to analyze how greenhouse gases could evolve this century and to evaluate probabilities of additional warming to Brazil based on climate projections. The results are shown in values for average temperature and anomalies close to the surface. Thus, the probabilities for a range of different warming levels were obtained exceeding by 4 °C to 7 °C for RCP 8.5. In this scenario, Brazil shows a 100% probability of suffering temperature rises of over 4 °C before the end of this century. For more extreme warming as 7 °C, the probability is of 80% by 2200. The Brazil analysis serves two purposes: a) plausible adaptation strategies require local risk knowledge; and b) the focus on higher warming temperature changes is crucial for a cost-benefit analysis of mitigation policies to reduce the risks of impacts and damages caused by extreme regional climate change. Apparently small changes in the climate may have significant effects, especially if important thresholds are surpassed. Crops have little tolerance to high temperatures, and as the climate gets warmer, these limits may be exceeded more and more often. This is one of the reasons why temperatures rise of 4 °C or more might represent severe risks for global food safety and affect food-producing countries like Brazil.

Tthe possible impacts of climate change in the vulnerability of agricultural production will be analysed considering a increase in temperature of 3 °C or more until the end of the century. In order to analyse agricultural production it is important to remember that the study of the effects of the increase in temperature, should also be done together with other factors like for instance, water availability and the increase of CO₂concentration. The potential risks imposed by climate change to Brazilian agriculture justify investments in farming research, particularly in the genetic modification of crops. In addition, studies to quantify the nature of extreme events, for periods between 2050 and 2011 have to be conducted. Technological advances in the management of crops and the adoption of good farming practices may also minimise impacts expected. The importance of developing crops tolerant to higher temperatures and water deficit is emphasized. With temperature increasing over 4 °C, impacts suffered will be strong at magnitudes not yet known by science. The main conclusion is that in terms of food supply, temperature rises above 4 °C place Brazil in a very vulnerable situation, compromising its current role of the future’s main player in relation to providing food to the world.

Climate change poses risks to biodiversity and to the socioecological systems dependent on it in Brazil. However, the country’s natural wealth, its biodiversity and ecosystems, are simultaneously among the main source of alternatives for mitigation and adaptation. This review shows that increase in temperature of >2^oC, towards the end of this century, will have severe impacts upon biodiversity in Brazil. Impacts include high rates of species extinction, geographic dislocation of species (particularly towards the south), savannization of forests and impoverishment of savanna and other open vegetation, significant reductions in the number of days of growth per year for tropical forest species, and impacts on agriculture due to decline in populations of important pollinators. Most Brazilian biomes are particularly sensitive to climate change and ecosystem such as those at high-altitude, coastal and marine, and urban areas are largely vulnerable. Ecosystem-based adaptation to climate change emerges as a key option for Brazil to reduce societal vulnerability. Science and policy related to biodiversity conservation and ecological restoration will need to incorporate climate change background on prioritisation efforts and implementation. The main conclusion of this review is that bringing biodiversity and ecosystems to the centre of the development process of Brazil, rather than treating them as an obstacle to development, will be a strategic step both to fight climate change and to promote a sustainable and inclusive development.

Among the contributors to the increase in the concentration of greenhouse gases (GHG), the energy sector stands out as an important climate change driving force. On the other hand, the energy sector is vulnerable to changes in climate. This is especially true for renewable energy sources, which show higher vulnerability when compared to non-renewable sources like coal, oil and gas. Paradoxically, thus, the options to reduce GHG emissions from energy combustion are those that are more exposed to the very impacts of those emissions. Therefore, it is important to assess the vulnerability of the energy system, in general and of renewable energy in particular, to climate change. The objective of this chapter is to assess what would be the effects of extreme climate change, in other words, with average temperature increase of over 4 °C, on the Brazilian energy system in different settings. This chapter is based on a review of climate change impact studies that have been conducted for Brazil. Since the Brazilian power sector is highly based on hydropower, most studies have focused on climate change impacts on hydropower. The analysis shows that in extreme climate scenarios a vicious cycle would emerge. An increase in demand for electricity would result from global warming, while energy production would fall short in its supply, as temperature increases would affect renewable sources mostly. These results do not depend on future settings for the Brazilian energy system, as renewable sources should remain predominant in the medium-long term.

Although semiarid vegetation is usually resistant and highly resilient to water deficits, vegetation activity in semiarid region of Northeast Brazil (NEB) is highly controlled by interannual variations in water availability and decrease in water availability may trigger land degradation and desertification. Recurrent droughts conditions in semiarid regions, such as NEB, can produce a progressive loss of resilience that affects negatively vulnerable populations living from small-scale agriculture. The drought affecting this region continuously during the last 7 years shows an intensity and impact not seen in several decades in the regional economy and society, and represents an example oh what could happen in NEB in the future. In sum, regional warming above 4 °C is likely to increase the drought risk in Northeast Brazil, with increase temperature and decrease precipitation resulting in lower vegetal productivity and more unpredictable harvests. In municipalities, where smallholder livelihoods are not very diversified and are dominated by subsistence agriculture, even a moderate drought (as in 2012–13) can cause a decline in harvests; and, with an increased drought risk (as the future projections), the harvest scenario can still be worse and devastating for regional and national food security and economy. Therefore, there is an urgent need for proactive drought management and preparedness strategies as well as integrated assessments considering the synergy of impacts and limits to adaptation in multiple sectors and regions in a 4 °C warming for NEB.

The Amazonian forest’s ability to provide environmental services is threatened by anthropogenic forcing at various scales, such as deforestation, fire, global and regional climate change, and extreme events. In addition to the impacts resulting from each one of these drivers, the synergistic effects potentially increase the risks. In the light of the above, this chapter aims to evaluate the future prospects for the Amazon in a scenario of 4 °C or higher warming resulting from anthropogenic climate change and the related hydrological cycle changes. Future climate scenarios project progressively higher warming that may exceed 4 °C in Amazonia in the second half of the century, particularly during the dry season in the region. Associated with these scenarios, it is projected a reduction of precipitation year-round, being a substantial reduction predominantly in the dry and transition seasons and smaller reductions of the order of 5% for the SH summer. Evaluating the consequences of such substantial climatic change, several negative effects in Amazonia can be anticipated, including short-term hydrological changes similar to the events associated to the extreme 2005 and 2010 droughts, and longer time-scale modifications of broad scale characteristics such as different biome distribution. Based on hydrological models, it is generally expected a reduction in river discharges associated to precipitation decreases and temperature increases brought about by projected climate change, but with the magnitude of the changes differing between models. The future climate change scenarios imply important changes in biomes distribution over Amazonia, with potential expansion of savannah and caatinga over large areas currently occupied by tropical forests. It is necessary a reduction to nearly zero in tropical deforestation and reducing land-cover emissions and mitigating climate change to avoid a dangerous interference with the ability of natural ecosystems to adapt to these possible changes.

Studies related to climate change scenarios and their impacts in key sectors of the Brazil need to be addressed. Measures to address the climate change impacts identified in the Brazilian energy, water agriculture and biodiversity sectors need to be implemented. Risk assessments for these sectors, as well as others such as water resources, urban areas, sea level rise and natural disasters are essential to assist in understanding problems and threats consequence of a dangerous climate change due to warming about 4 °C, particularly in regions and sectors of Brazil that are already vulnerable to the extremes of climate variability. There is a need to minimize climate risks means influencing the developing of policies that prioritise the mitigation of emissions, as well as adaptation to future scenarios. Therefore, policy makers should address climate change as a risk management issue. As shown by this book, assessing the impacts of extreme climate events due to a warming above 4 °C on the energy, agricultural, health and biodiversity sectors is very complex.