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Topic Review
Clathrate Gun Hypothesis
The clathrate gun hypothesis refers to a proposed explanation for the periods of rapid warming during the Quaternary. The idea is that changes in fluxes in upper intermediate waters in the ocean caused temperature fluctuations that alternately accumulated and occasionally released methane clathrate on upper continental slopes, these events would have caused the Bond Cycles and individual interstadial events, such as the Dansgaard–Oeschger interstadials. The hypothesis was supported for the Bølling-Allerød and Preboreal period, but not for Dansgaard–Oeschger interstadials, although there are still debates on the topic.
  • 1.2K
  • 18 Oct 2022
Topic Review
Clays and the Origin of Life
Clays are able to replicate and drive the evolution of metabolism; they have the catalytic ability to synthesize monomers (amino acids, nucleotides and so on) and polymerize them, resulting in RNA–peptide worlds in which RNA replicates (genes) and, in cooperation with coded peptides, drives the evolution of the cell. 
  • 2.1K
  • 25 Feb 2022
Topic Review
Clean Development Mechanism
The Clean Development Mechanism (CDM) is one of the Flexible Mechanisms defined in the Kyoto Protocol (IPCC, 2007) that provides for emissions reduction projects which generate Certified Emission Reduction units (CERs) which may be traded in emissions trading schemes. The market crashed in 2012 when the value of credits collapsed and thousands of projects were left with unclaimed credits. The struggle about what to do with the old credits sank the 2019 COP 25 in Madrid. The CDM, defined in Article 12 of the Protocol, was intended to meet two objectives: "Annex I" parties are the countries listed in Annex I of the treaty, the industrialized countries. Non-Annex I parties are developing countries. The CDM addresses the second objective by allowing the Annex I countries to meet part of their emission reduction commitments under the Kyoto Protocol by buying Certified Emission Reduction units from CDM emission reduction projects in developing countries. Both the projects and the issue of CERs units are subject to approval to ensure that these emission reductions are real and "additional." The CDM is supervised by the CDM Executive Board (CDM EB) under the guidance of the Conference of the Parties (COP/MOP) of the United Nations Framework Convention on Climate Change (UNFCCC). The CDM allows industrialized countries to buy CERs and to invest in emission reductions where it is cheapest globally. Between 2001, which was the first year CDM projects could be registered and 7 September 2012, the CDM issued 1 billion Certified Emission Reduction units. As of 1 June 2013, 57% of all CERs had been issued for projects based on destroying either HFC-23 (38%) or N2O (19%). Carbon capture and storage (CCS) was included in the CDM carbon offsetting scheme in December 2011. However, a number of weaknesses of the CDM have been identified. Several of these issues were addressed by the new Program of Activities (PoA), which moves to approving 'bundles' of projects instead of accrediting each project individually. In 2012, the report Climate Change, Carbon Markets and the CDM: A Call to Action said governments urgently needed to address the future of the CDM. It suggested the CDM was in danger of collapse because of the low price of carbon and the failure of governments to guarantee its existence into the future. Writing on the website of the Climate & Development Knowledge Network, Yolanda Kakabadse, a member of the investigating panel for the report and founder of Fundación Futuro Latinamericano, said a strong CDM is needed to support the political consensus essential for future climate progress. "Therefore we must do everything in our hands to keep it working," she said.
  • 1.1K
  • 17 Oct 2022
Topic Review
Cleaning Technologies for Indoor Air Quality Improvement
If outdoor air is more polluted, or in certain situations where ventilation is not possible, other strategies need to be applied, such as source control and pollutants extraction. The latter incorporates air cleaning technologies, one of the emergent areas of indoor air quality. Various air treatment technologies can be used to control contaminants, including physicochemical technologies and biological technologies.
  • 549
  • 28 Sep 2022
Topic Review
Cleveland-Lloyd Dinosaur Quarry
The Cleveland-Lloyd Dinosaur Quarry, well known for containing the densest concentration of Jurassic dinosaur fossils ever found, is a paleontological site located near Cleveland, Utah, in the San Rafael Swell, a part of the geological layers known as the Morrison Formation. Well over 15,000 bones have been excavated from this Jurassic excavation site and there are many thousands more awaiting excavation and study. It was designated a National Natural Landmark in October 1965. All of these bones, belonging to different species, are found disarticulated and indistinctly mixed together. It has been hypothesised that this strong concentration of mixed fossilised bones is due to a "predator trap", but any kind of definitive scientific consensus hasn't been reached yet and debates still continue to the present day.
  • 503
  • 17 Oct 2022
Topic Review
Climate Across Cretaceous–Paleogene Boundary
The climate across the Cretaceous–Paleogene boundary (K–Pg or formerly the K–T boundary) is very important to geologic time as it marks a catastrophic global extinction event. Numerous theories have been proposed as to why this extinction event happened including an asteroid known as the Chicxulub asteroid, volcanism, or sea level changes. While the mass extinction is well documented, there is much debate about the immediate and long-term climatic and environmental changes caused by the event. The terrestrial climates at this time are poorly known, which limits the understanding of environmentally driven changes in biodiversity that occurred before the Chicxulub crater impact. Oxygen isotopes across the K–T boundary suggest that oceanic temperatures fluctuated in the Late Cretaceous and through the boundary itself. Carbon isotope measurements of benthic foramifinera at the K–T boundary suggest rapid, repeated fluctuations in oceanic productivity in the 3 million years before the final extinction, and that productivity and ocean circulation ended abruptly for at least tens of thousands of years just after the boundary, indicating devastation of terrestrial and marine ecosystems. Some researchers suggest that climate change is the main connection between the impact and the extinction. The impact perturbed the climate system with long-term effects that were much worse than the immediate, direct consequences of the impact.
  • 628
  • 25 Nov 2022
Topic Review
Climate and Surfing
Surfing is one of the most popular activities in coastal tourism resorts. However, the sport depends strongly on the met-ocean weather conditions, particularly on the surface wind-generated waves that reach the coast.
  • 460
  • 26 Jul 2022
Topic Review
Climate Apocalypse
A climate apocalypse (also called a climate dystopia and a climate-induced collapse, among other names) is a hypothetical scenario involving the global collapse of human civilization and potential human extinction as either a direct or indirect result of anthropogenic climate change and ecological breakdown. Under a global catastrophe of this scale, some or all of the Earth may be rendered uninhabitable as a result of extreme temperatures, severe weather events, an inability to grow crops, and an altered composition of the Earth's atmosphere. Although there is consensus on the attribution of recent climate change to human activity, and concern about future tipping points and feedback loops, there is no consensus on the likelihood of climate-induced collapse.
  • 1.7K
  • 17 Oct 2022
Topic Review
Climate Audit
Climate Audit is a blog which was founded on 31 January 2005 by Steve McIntyre. In November 2009 journalist Andrew Revkin described it in The New York Times as "a popular skeptics’ blog" run by McIntyre, a retired Canadian mining consultant.
  • 790
  • 21 Nov 2022
Topic Review
Climate Causal Flows
Physical processes govern climate at different spatial and temporal scales. These physical processes themselves constitute the transfer or flow of energy and mass. Causality methods have been used in recent years to study the flow of energy and mass. These methods give an indication of the direction of the flow and the intensity of the transfer. Climatic causal flows refer to hypotheses about physical processes that have been discovered using causal inference methods.
  • 778
  • 27 Jan 2022
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