Since tropical rainfall is important in the global energy and hydrologic cycle, the tropical rainfall changes under global warming have attracted extensive attention around the world in recent decades. The advances in the observational studies and model projection for the tropical rainfall changes under global warming were reviewed here. The frontiers in the mechanism of regional tropical rainfall changes and the approaches of rainfall change research are summarized. The large intermodel spread in the multi-model projections, the sources of uncertainty and the methods to reduce the uncertainty were also introduced. Finally, the challenges about the tropical rainfall changes were discussed. 相似文献
The thermodynamics of the seasonal evolution of the Southwestern Tropical Atlantic Warm Pool (hereafter SWTAWP), which is delimited by the 28 °C isotherm, is investigated using the Regional Ocean Modeling System (ROMS). Results indicate that the net heat flux is responsible for the appearance and extinction of the SWTAWP. From March to May, the SWTAWP attains its maximum development and sometimes merges with equatorial warm waters towards the African continent, whose development follows the same period. Along the equator, the combination of oceanic terms (i.e., advection and diffusion) is important to promote the separation – when it occurs – of equatorial warm waters from southwestern tropical waters, which develops off the Brazilian coast. An analysis of the relative contribution of the temperature tendency terms of the mixed layer (ML) heat budget over the appearance, development and extinction of the SWTAWP is also done. The most important term for warming and cooling inside of the ML is the net heat flux at the sea surface. The ML is heated by the atmosphere between October and April, whereas the upper ocean cools down between May and September. The highest heat content values occur during the lower-temperature period (August to October), which is linked to the deepening of the ML during this time period. The horizontal advection along the equator is important, particularly at the eastern domain, which is influenced by the cold tongue. In this area, the vertical diffusive term is also significant; however, it presents values near zero outside the equator. These results contribute to a better understanding of the behavior of the heat budget within the tropical Atlantic, as previous studies over this region focused along the equator only. 相似文献
Nearly all long-term energy projections rely heavily on renewable energy sources on the assumption of abundance. Yet, already today, wind and solar projects can encounter local objections and competition with other uses. This paper presents the ranges of realistic potential supply for solar and wind electricity, using a 1 km2 grid level analysis covering the whole world at country level. In addition, the potential for building-based solar electricity is assessed. We find that long-term combined potentials range between 730 and 3700 EJ/a worldwide, depending crucially on the acceptable share of land—up to 3.5% of total (non-ice covered) land on earth. Realistic potentials account for limitations such as land-use competition and acceptance, together with resource quality and remoteness as proxies for cost. Today's electricity demand (65 EJ/a) is well covered by the range, but constraints may occur in the long run locally. Amongst large countries, Nigeria and India may need imports to meet electricity demand. 相似文献
Limiting global warming to ‘well below’ 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase even further to 1.5°C is an integral part of the 2015 Paris Agreement. To achieve these aims, cumulative global carbon emissions after 2016 should not exceed 940 – 390?Gt of CO2 (for the 2°C target) and 167 – ?48?Gt of CO2 (for the 1.5°C target) by the end of the century. This paper analyses the EU’s cumulative carbon emissions in different models and scenarios (global models, EU-focused models and national carbon mitigation scenarios). Due to the higher reductions in energy use and carbon intensity of the end-use sectors in the national scenarios, we identify an additional mitigation potential of 26–37 Gt cumulative CO2 emissions up to 2050 compared to what is currently included in global or EU scenarios. These additional reductions could help to both reduce the need for carbon dioxide removals and bring cumulative emissions in global and EU scenarios in line with a fairness-based domestic EU budget for a 2°C target, while still remaining way above the budget for 1.5°C.Key policy insights
Models used for policy advice such as global integrated assessment models or EU models fail to consider certain mitigation potential available at the level of sectors.
Global and EU models assume significant levels of CO2 emission reductions from carbon capture and storage to reach the 1.5°C target but also to reach the 2°C target.
Global and EU model scenarios are not compatible with a fair domestic EU share in the global carbon budget either for 2°C or for 1.5°C.
Integrating additional sectoral mitigation potential from detailed national models can help bring down cumulative emissions in global and EU models to a level comparable to a fairness-based domestic EU share compatible with the 2°C target, but not the 1.5°C aspiration.
The successful implementation of the Paris Agreement requires substantial energy policy change on the national level. In national energy policy-making, climate change mitigation goals have to be balanced with arguments on other national energy policy goals, namely limiting cost and increasing energy security. Thus far, very little is known about the relative importance of these goals and how they are related to political partisanship. In order to address this gap, we focus on parliamentary discourse around low-carbon energy futures in Germany over the past three decades and analyze the relative importance of, and partisanship around, energy policy goals. We find that the political discourse revolves around four, rather than three, goals as conventionally assumed; improving the competitiveness of the national energy technology industry is not only an additional energy policy goal, it is also highly important in the political discourse. In general, the relative importance of these goals is rather stable over time and partisanship around them is limited. Yet, a sub-analysis of the discourse on renewable energy technologies reveals a high level of partisanship, albeit decreasing over time. Particularly, the energy industry goal’s importance increases while its partisanship vanishes. We discuss how these findings can inform future energy policy research and provide a potential inroad for more ambitious national energy policies.
Key policy insights
In addition to the three classic goals of energy policy (limiting cost, securing access and reducing the environmental burden) we identify a fourth policy goal: strengthening the national energy technology industry
Conformity between the three classical energy and the industrial policy goals is a key driver explaining policy change
For renewable energy technologies, partisanship around this fourth goal is lower than around other goals and decreases over time as innovation allows these technologies to increasingly correspond to policy-makers’ high-level goals
Extant research underestimates the importance of industry policy goals, but overestimates environmental co-benefits of low-carbon energy options
Paradigmatic policy change in Germany did not depend on top-down shifts in high-level policy goals but was driven by lower-level technology-specific goals