RealClimate is wonderful, and an excellent source of reliable information.As I've said before, methane is an extremely dangerous component to global warming.Comment # 20 is correct.There is a sharp melting
point to frozen methane.A huge increase in the release of methane could happen within the next 50 years.At what
point in the Earth's temperature rise and the rise of co2 would a huge methane melt occur?No one has answered that definitive issue.If I ask you all at what
point would huge amounts of extra methane start melting, i.e at what temperature rise of the ocean near the Artic methane ice deposits would the methane melt, or at what
point in the rise of co2 concentrations in the atmosphere would the methane melt, I believe that no one could currently tell me the actual answer as to where the sharp melting
point exists.Of course, once that tipping
point has been reached, and billions of tons of methane outgass from what had been locked stores of methane, locked away for an eternity, it is exactly the same as the burning of stored fossil fuels which have been stored for an eternity as well.And even though methane does not have as long a life as co2, while it is around in the air it can cause other tipping
points, i.e. permafrost melting, to arrive much sooner.I will reiterate what I've said before on this and other sites.Methane is a hugely underreported, underestimated risk.How about RealClimate attempts to model exactly what would happen to other tipping
points, such as the melting permafrost, if indeed a huge increase in the melting of the methal hydrate ice WERE to occur within the next 50 years.My amateur guess is that the huge, albeit temporary, increase in methane over even three or four decades might push other relevent tipping
points to arrive much, much, sooner than they normally would, thereby vastly incresing
negative feedback mechanisms.We KNOW that quick, huge, changes occured in the Earth's climate in the past.See other relevent posts in the past from Realclimate.Climate often does not change slowly, but undergoes huge, quick, changes periodically, due to
negative feedbacks
accumulating, and tipping the climate to a quick change.Why should the danger from huge potential methane releases be vievwed with any less trepidation?
Criteria Description Fish Toxicity Measure of the acute toxicity to fish (both saltwater and freshwater) Daphnia Toxicity Measure of the acute toxicity to Daphnia (invertebrate aquatic organisms) Algae Toxicity Measure of the acute toxicity to aquatic plants Persistence / Biodegradation Rate of degradation for a substance in the environment (air, soil, or water) Bioaccumulation Potential for a substance to
accumulate in fatty tissue and magnify up the food chain Climatic relevance Measure of the impact a substance has on the climate (e.g., ozone depletion, global warming, etc.) Other Any additional characteristic (e.g., soil organism toxicity, WGK water classification, etc.) relevant to the overall evaluation but not included in the previous criteria 1.3.3 Material Class Criteria The following material classes are flagged due to the concern that at some
point in their life cycle they may have
negative impacts on human and environmental health.