Hello and welcome to another session of this course. Within the many different impacts of climate change, some of the most noticeable are the impacts of climate change on the so-called physical systems and by physical systems I refer here to a marine physical systems and those include impacts into seas and oceans, freshwater physical systems, and those refer to impacts on continental water bodies such as rivers and lakes. The cryosphere, which refers to impacts on the water that is in the form of ice in our planet and on the rest of physical systems that refer to climate change impacts on soils and land. Although all these impacts are connected and mutually influence each other for the sake of clarity, I will present them here under these categories and I will bring some examples of some of the most important changes in these different physical systems and how these changes are bringing impacts to indigenous peoples and local communities across the world. The main climate change impacts to the cryosphere refers to impact on snow cover, on lake and river ice, on sea ice, and mostly on Arctic or Antarctic zones, on glaciers, and on permafrost, which is basically the frozen soils. Similarly to many other impacts of climate change, climate change impacts on the cryosphere that can have many different cascading impacts to other physical systems but also to other biological systems and social-ecological systems. One example of the climate change impacts on the cryosphere refers to changes in the sea ice, mostly in Arctic and Antarctic zones and these changes on the ice on these areas are bringing significant challenges to the community that inhabit this area as in the case of these Inuit communities that inhabit the Baffin islands in the North of Canada. These communities that had been reporting several changes in the ice sheets, including changes in the ice thickness, and changes in the seasonal dynamics of ice and this they say is bringing them several challenges regarding their different activities such as restraining their mobility across the ice and increasing their risks when they do so. Another example of climate change impacts to the cryosphere refers to changes in glaciers, so glaciers have been melting all over the world and especially in the last few decades. Glaciers, they have a profound influence on hydrological dynamics affecting properties such as streamflow, river discharge, or water quantity and quality and therefore, these changes in the glaciers, the melting of the glaciers can have many consequences to ecosystems and communities, both mountain communities but also downstream communities. This here is an example of the Cordillera Blanca in Peru, which is one of the largest tropical glaciers in the world. Melting glaciers had been reported in this region and these had been leading to several changes in the hydrological regime and reducing the water security of the populations that depend on the water that comes from these glaciers and increasing conflicts related to access to water. Regarding the climate change impacts on marine physical systems, these include impacts on sea level, on sea temperature, on ocean currents, on coastal erosion, and sedimentation, and also changes in properties of the ocean waters such as the salinity or the concentration of the CO_2 that is dissolved in the oceans. Sea level rise is perhaps one of the most iconic examples of climate change. So sea level has risen quite a lot in the last century or so, it has risen about 25 centimeters and nowadays it's rising on an even faster pace of about one centimeter every three years or so. These changes are expected to intensify in the future regardless of the climactic scenario that we consider. Although coastal zones that are located below 10 meters of elevation above the sea level only occupy around two percent of the land surface, about 10 percent of the population of the world live in these areas so this impacts of sea level rise can have significant impacts to very large populations that occupy coastal zones across the world. Among these, the ones that are and will be more particularly affected are populations that live in urban atoll islands, for example, or in large tropical agricultural deltas, or arctic communities. Sea level rise can have many different cascading effects and lead, for example, to the increase in several coastal hazards. These include, for example, the enhanced flooding of coastal zones, the increased salinity of coastal soils, or the submergence of land or coastal erosion, as you can see here on this picture that it's an example from Kiribati which is one of the lowest countries in the world that has been directly impacted by sea level rise in recent years. These changes in coastal hazards driven by sea level rise it can have multiple impacts to the ecosystem services provided by coastal areas and therefore for all the human communities that inhabit and that depend on these areas for their subsistence and for their different livelihoods. Another example of changes in marine physical systems refer to changes in ocean currents. This here is an example from the South Western Africa where local fishing communities have been reporting many changes in the dynamics of ocean currents. This has been bringing them many challenges regarding their main livelihood activity, which is fishing. Together with the other ongoing socioeconomic pressures, the climate change impacts on ocean currents in this area is increasing the vulnerability of these communities. Here's an example of how climate change can overlap with other pressures and increase the vulnerability of local communities. Regarding the climate change impact on terrestrial physical systems these mostly referred to impact in soils. Changes in rainfall patterns or in wind patterns or the increased occurrence of extreme events. These all can have several consequences to soils and leading to changes in soil erosion and landslides in soil moisture, temperature, and fertility. Changes in soil are also largely driven by local land use changes. But when these changes are overlapped with climatic change, they tend to be exacerbated. Here in this figure, we see the predictions to the next century regarding the level of soil erosion, which results from this combination of land-use changes in climate change. As we can see here, the red areas, they indicate areas where soil erosion is expected to increase in the future due to the combined effects of climate change and local land use. Changes in terrestrial physical systems are already ongoing and are also expected to intensify in the future. These changes in soil, there are very much related to the process of desertification. Actually desertification is driven by multiple factors to which climate change contributes substantially. Desertification can also have multiple consequences, as we can see here in this figure, this represents the many different negative impacts that desertification can have on local communities and on ecosystems represented here by the different UN sustainable development goals. In some countries, desertification is already a reality, such as Mali, for example, depicted here on this picture on the top right, where a large part of the country is already under severe risk of desertification and this is also expected to be intensified due to the effects of climate change. Last but not least, the climate change impacts on freshwater physical systems, those referred to impacts in continental waters such as rivers, lakes, streams, and also groundwater. These changes they include, for example, changes in water flow and volume, changes in the hydrological dynamics of these water bodies or what processes changing, for example, the dynamics of floods or seasonal fluctuations of rivers or lakes, changes in the freshwater availability or quality we just particularly relevant for human populations. Changes in characteristics of the waters, the temperature or dissolved sediment, and also changes in areas associated or surrounding water bodies, such as changes in the erosion of banks around rivers or around lakes. Here's an example of local communities in the Nepal Himalayas, where the local communities in this region have been reporting substantial decreases in the number of streams so water streams, and also in the volume of water on these streams. This has been bringing significant impacts of these populations, not only because they consume water from those springs, but also because these springs provide water that they use for other activities such as irrigation. As we can see here on this map, all these different points like the red and all the different points here that represent streams that were identified by local communities as streams that have been changing, either drying completely, or by reducing substantially the amount of water that they provide. This is an example of changes in freshwater physical systems that has profiling bags in local communities in livelihoods. Just a few take home messages to wrap up. Climate change has multiple effects on different physical systems of our planet. Those include changes in the cryosphere, changes in the marine physical systems, in terrestrial physical systems, and in freshwater physical systems. These changes in physical systems, just like many other climatic changes, they have several cascading consequences for other systems, or other biological systems, and other social-ecological systems. This is particularly relevant in the context of indigenous peoples and local communities whose livelihoods are essentially based on natural resources that are sustained by these physical systems. Thank you very much for your attention.
