Not Half Bad

Author(s):  
Scott E. Page

To understand a complex system (e.g., an economy, an ecosystem, the global climate system), scientists often rely on models. Models simplify reality by focusing on certain parts of a system, and the relationships between them, while ignoring, by necessity, other. Advocates of complexity theory often boldly claim (partly by virtue of greater realism) that they can improve upon the standard neoclassical economic framework. A much weaker claim supports the promotion of this new class of models or any class of models: even if the complexity framework makes less accurate predictions than the neoclassical approach, the complexity framework can be of use because its models differ.

Author(s):  
Richard Passarelli ◽  
David Michel ◽  
William Durch

The Earth’s climate system is a global public good. Maintaining it is a collective action problem. This chapter looks at a quarter-century of efforts to understand and respond to the challenges posed by global climate change and why the collective political response, until very recently, has seemed to lag so far behind our scientific knowledge of the problem. The chapter tracks the efforts of the main global, intergovernmental process for negotiating both useful and politically acceptable responses to climate change, the UN Framework Convention on Climate Change, but also highlights efforts by scientific and environmental groups and, more recently, networks of sub-national governments—especially cities—and of businesses to redefine interests so as to meet the dangers of climate system disruption.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tainã M. L. Pinho ◽  
Cristiano M. Chiessi ◽  
Rodrigo C. Portilho-Ramos ◽  
Marília C. Campos ◽  
Stefano Crivellari ◽  
...  

AbstractSubtropical ocean gyres play a key role in modulating the global climate system redistributing energy between low and high latitudes. A poleward displacement of the subtropical gyres has been observed over the last decades, but the lack of long-term monitoring data hinders an in-depth understanding of their dynamics. Paleoceanographic records offer the opportunity to identify meridional changes in the subtropical gyres and investigate their consequences to the climate system. Here we use the abundance of planktonic foraminiferal species Globorotalia truncatulinodes from a sediment core collected at the northernmost boundary of the South Atlantic Subtropical Gyre (SASG) together with a previously published record of the same species from the southernmost boundary of the SASG to reconstruct meridional fluctuations of the SASG over last ca. 70 kyr. Our findings indicate southward displacements of the SASG during Heinrich Stadials (HS) 6-4 and HS1, and a contraction of the SASG during HS3 and HS2. During HS6-4 and HS1, the SASG southward displacements likely boosted the transfer of heat to the Southern Ocean, ultimately strengthening deep-water upwelling and CO2 release to the atmosphere. We hypothesize that the ongoing SASG poleward displacement may further increase oceanic CO2 release.


2014 ◽  
Vol 6 (1) ◽  
pp. 619-655
Author(s):  
S. Zubrzycki ◽  
L. Kutzbach ◽  
E.-M. Pfeiffer

Abstract. Permafrost-affected soils have accumulated enormous pools of organic matter during the Quaternary Period. The area occupied by these soils amounts to more than 8.6 million km2, which is about 27% of all land areas north of 50° N. Therefore, permafrost-affected soils are considered to be one of the most important cryosphere elements within the climate system. Due to the cryopedogenic processes that form these particular soils and the overlying vegetation that is adapted to the arctic climate, organic matter has accumulated to the present extent of up to 1024 Pg (1 Pg = 1015 g = 1 Gt) of soil organic carbon stored within the uppermost three meters of ground. Considering the observed progressive climate change and the projected polar amplification, permafrost-affected soils will undergo fundamental property changes. Higher turnover and mineralization rates of the organic matter are consequences of these changes, which are expected to result in an increased release of climate-relevant trace gases into the atmosphere. As a result, permafrost regions with their distinctive soils are likely to trigger an important tipping point within the global climate system, with additional political and social implications. The controversy of whether permafrost regions continue accumulating carbon or already function as a carbon source remains open until today. An increased focus on this subject matter, especially in underrepresented Siberian regions, could contribute to a more robust estimation of the soil organic carbon pool of permafrost regions and at the same time improve the understanding of the carbon sink and source functions of permafrost-affected soils.


1998 ◽  
Vol 08 (04) ◽  
pp. 799-803 ◽  
Author(s):  
D. M. Sonechkin

Based on the heat balance equation of the global climate system the well-known surface air temperature time series of the Northern and Southern hemispheres were analyzed as realizations of a fractional Brownian motion. The technique of the so-called wavelet transform was used for this purpose. The technique easily admits splitting time series of interest to statistically stationary oscillations and a trend. Such temperature oscillations were extracted which include within themselves almost all differences between both hemispheric time series. As a result of subtraction of the oscillations from the primary hemispheric series a residual trend-like component was evaluated. The latter evidences a single warming trend of the global climate system that was started from the early 20th century.


Author(s):  
Jose A. Marengo ◽  
Carlos A. Nobre

The Amazon region is of particular interest because it represents a large source of heat in the tropics and has been shown to have a significant impact on extratropical circulation, and it is Earth’s largest and most intense land-based convective center. During the Southern Hemisphere summer when convection is best developed, the Amazon basin is one of the wettest regions on Earth. Amazonia is of course not isolated from the rest of the world, and a global perspective is needed to understand the nature and causes of climatological anomalies in Amazonia and how they feed back to influence the global climate system. The Amazon River system is the single, largest source of freshwater on Earth. The flow regime of this river system is relatively unimpacted by humans (Vörösmarty et al. 1997 a, b) and is subject to interannual variability in tropical precipitation that ultimately is translated into large variations in downstream hydrographs (Marengo et al. 1998a, Vörösmarty et al. 1996, Richey et al. 1989a, b). The recycling of local evaporation and precipitation by the forest accounts for a sizable portion of the regional water budget (Nobre et al. 1991, Eltahir 1996), and as large areas of the basin are subject to active deforestation there is grave concern about how such land surface disruptions may affect the water cycle in the tropics (see reviews in Lean et al. 1996). Previous studies have emphasized either how large-scale atmospheric circulation or land surface conditions can directly control the seasonal changes in rainfall producing mechanisms. Studies invoking controls of convection and rainfall by large-scale circulation emphasize the relationship between the establishment of upper-tropospheric circulation over Bolivia and moisture transport from the Atlantic ocean for initiation of the wet season and its intensity (see reviews in Marengo et al. 1999). On the other hand, Eltahir and Pal (1996) have shown that Amazon convection is closely related to land surface humidity and temperature, while Fu et al. (1999) indicate that the wet season in the Amazon basin is controlled by both changes in land surface temperature and the sea surface temperature (SST) in the adjacent oceans, depending if the region is north-equatorial or southern Amazonia.


Author(s):  
Cynthia Rosenzweig ◽  
Daniel Hillel

The climate system envelops our planet, with swirling fluxes of mass, momentum, and energy through air, water, and land. Its processes are partly regular and partly chaotic. The regularity of diurnal and seasonal fluctuations in these processes is well understood. Recently, there has been significant progress in understanding some of the mechanisms that induce deviations from that regularity in many parts of the globe. These mechanisms include a set of combined oceanic–atmospheric phenomena with quasi-regular manifestations. The largest of these is centered in the Pacific Ocean and is known as the El Niño–Southern Oscillation. The term “oscillation” refers to a shifting pattern of atmospheric pressure gradients that has distinct manifestations in its alternating phases. In the Arctic and North Atlantic regions, the occurrence of somewhat analogous but less regular interactions known as the Arctic Oscillation and its offshoot, the North Atlantic Oscillation, are also being studied. These and other major oscillations influence climate patterns in many parts of the globe. Examples of other large-scale interactive ocean–atmosphere– land processes are the Pacific Decadal Oscillation, the Madden-Julian Oscillation, the Pacific/North American pattern, the Tropical Atlantic Variability, the West Pacific pattern, the Quasi-Biennial Oscillation, and the Indian Ocean Dipole. In this chapter we review the earth’s climate system in general, define climate variability, and describe the processes related to ENSO and the other major systems and their interactions. We then consider the possible connections of the major climate variability systems to anthropogenic global climate change. The climate system consists of a series of fluxes and transformations of energy (radiation, sensible and latent heat, and momentum), as well as transports and changes in the state of matter (air, water, solid matter, and biota) as conveyed and influenced by the atmosphere, the ocean, and the land masses. Acting like a giant engine, this dynamic system is driven by the infusion, transformation, and redistribution of energy.


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