For the future, rainfall deficit added to increases in temperature in months when the rainy season ends on Colombia’s Eastern Plains (September to October) could produce decreases in available water for agriculture. Photo Neil Palmer (CIAT). Colombia’s Eastern Plains.
To anticipate future climate change, we need to project how greenhouse gases (GHG) will change in the next decades, which we can do from “emissions scenarios.” Emissions scenarios have been modeled to explain the potential consequences of human activities for climate. These scenarios are future representations of GHG in terms of some assumptions such as changes in population growth, socioeconomic development, and technology advances. Of course, we never know how anthropogenic emissions will change; however, the Intergovernmental Panel on Climate Change (IPCC) has developed four scenarios called Representative Concentration Pathways (RCP), which show projections based on low to high GHG emissions.
In the Orinoquia Integrated Climate Change Action Plan called “Orinoquia, together against climate change” (CIAT–Cormacarena agreement), we simulated climate change scenarios to project the likely futures of regional climate conditions toward a medium-term time horizon (2040s). This time frame is relevant for decision making in environmental management and is aligned with the national action plan. Some relevant results are described here.
Climate projections on Colombia’s Eastern Plains by 2040 (click on the left/right arrows to see changes in each variable, and click on the maps for more information).
The results show changes in annual precipitation ranging from decreases of ‒5% to increases up to 8%. The higher increases would take place in the southern region and the decreases in the northeastern region. Arauca and Vichada are the only departments of the Orinoquia region showing a deficit in rainfall, although not significant.
The maximum annual temperature is projected to increase between 0.6‒2.3 °C and 0.3‒2.4 °C for minimum temperature, with a higher increase toward the eastern region. Because the rate of increase is higher for maximum temperature than for minimum temperature, we would expect more frequent high-temperature extremes and less frequent cool-temperature extremes. The daytime temperature range (the difference between maximum and minimum temperature) would be progressively higher over the years. Arauca, Casanare, and Vichada Departments show the highest temperature increases in the whole country, which is consistent with the information presented by IDEAM in the Third National Communication on Climate Change (TCN).
Compared with historical climate conditions, projections suggest increases in rainfall in almost the entire region and these would be higher in the dry season (December to January), with slight increases in the wetter months (May to August). Decreases in rainfall are projected at the end of the rainy season (September to October), especially toward Arauca and northern Vichada. This projection is very important in the agricultural context because this could mean that the rainy season would end earlier, which would translate into less water availability and less time for plant growth. In a pessimistic future scenario (high emissions), rainfall reductions could reach ‒25% when the rainy season ends in most of the region.
All months of the year are projected to be hotter than current conditions. Higher increases in temperature are exacerbated in the dry season, which increase evapotranspiration of crops even more, along with the amount of water required for irrigation. In northern and eastern Vichada, and in Arauca, increases in maximum and minimum temperature would occur for every month and in most emissions scenarios. The largest increases are projected in the departments of Arauca and Vichada. Temperature changes are homogeneous in Meta and Casanare in most municipalities, with an average increase in the maximum and minimum temperature of +1.3 °C and +1.4 °C, respectively (under the intermediate emissions scenario).
The goal of working with scenarios isn’t to predict the future but rather to better understand the uncertainties and alternative futures, in order to consider the soundness of different decisions or actions that can be undertaken within a broad range of possible options. Scenario modeling allows us to analyze climate projections for Colombia’s Eastern Plains, and it is a useful information resource for decision making in an agricultural and environmental context, to improve natural resource management in the region. All the information resulting from the Scenario Analysis is the basis for the impact assessment component carried out through crop, species, and water modeling that will be developed in other project components.
How did we do this?
We used 14 Global Climate Models (GCMs) of the IPCC Fifth Assessment Report (AR5), the same as those used by IDEAM for the Third National Communication on Climate Change (TCN). We used a statistical downscaling methodology, called the Delta method (for more information, visit the CCAFS-Climate portal), to obtain high-resolution data up to 1 km (scale of 1:100,000) showing sufficient detail to work at a sub-municipal level. We generated daily data for crop physiological modeling on more than 180,000 points, covering the whole geography of the Eastern Plains (excluding forested areas and nature parks) using MarkSim.
For further information, visit Orinoquia, juntos frente al cambio climático [Orinoquia, together against climate change].