[Sjaax]

Oorspronkelijk geplaatst door Voltian

Kan ik u verleiden om de Stern review te lezen of moet ik hier echt argumenteren? (op deze link vind je alles over zijn rapport: http://www.hm-treasury.gov.uk/stern_review_report.htm)

Stern schijft bvb in Part II: The Impacts of Climate Change on Growth and Development;
Hoofdstuk 3: How Climate Change Will Affect People Around The World

Key Messages
Climate change threatens the basic elements of life for people around the world – access to water, food, health, and use of land and the environment. On current trends, average global temperatures could rise by 2 - 3°C within the next fifty years or so,1 leading to many severe impacts, often mediated by water, including more frequent droughts and floods (Table 3.1).

• Melting glaciers will increase flood risk during the wet season and strongly reduce dry-season water supplies to one-sixth of the world’s population, predominantly in the Indian sub-continent, parts of China, and the Andes in South America.
• Declining crop yields, especially in Africa, are likely to leave hundreds of millions without the ability to produce or purchase sufficient food - particularly if the carbon fertilisation effect is weaker than previously thought, as some recent studies suggest. At mid to high latitudes, crop yields may increase for moderate temperature rises (2 – 3°C), but then decline with greater amounts of warming.
• Ocean acidification, a direct result of rising carbon dioxide levels, will have major effects on marine ecosystems, with possible adverse consequences on fish stocks.
• Rising sea levels will result in tens to hundreds of millions more people flooded each year with a warming of 3 or 4°C. There will be serious risks and increasing pressures for coastal protection in South East Asia (Bangladesh and Vietnam), small islands in the Caribbean and the Pacific, and large coastal cities, such as Tokyo, Shanghai, Hong Kong, Mumbai, Calcutta, Karachi, Buenos Aires, St Petersburg, New York, Miami and London.
• Climate change will increase worldwide deaths from malnutrition and heat stress. Vector-borne diseases such as malaria and dengue fever could become more widespread if effective control measures are not in place. In higher latitudes, cold-related deaths will decrease.
• By the middle of the century, 200 million more people may become permanently displaced due to rising sea levels, heavier floods, and more intense droughts, according to one estimate.
• Ecosystems will be particularly vulnerable to climate change, with one study estimating that around 15 – 40% of species face extinction with 2°C of warming. Strong drying over the Amazon, as predicted by some climate models, would result in dieback of the forest with the highest biodiversity on the planet.

The consequences of climate change will become disproportionately more damaging with increased warming. Higher temperatures will increase the chance of triggering abrupt and large-scale changes that lead to regional disruption, migration and conflict.

• Warming may induce sudden shifts in regional weather patterns like the monsoons or the El Niño. Such changes would have severe consequences for water availability and flooding in tropical regions and threaten the livelihoods of billions.
• Melting or collapse of ice sheets would raise sea levels and eventually threaten at least 4 million Km2 of land, which today is home to 5% of the world’s population.

Dit zijn alle verslechteringen. Dat lijkt op angstaanjagerij. Zo werkt het toch niet. Zelfs wanneer er een duidelijk positief effect optreedt, krijgt het uiteindelijk toch een negatieve draai: At mid to high latitudes, crop yields may increase for moderate temperature rises (2 – 3°C), but then decline with greater amounts of warming.

Wanneer de Noordpool smelt, dan is het inderdaad jammer voor de ijsbeer. De populatie zal decimeren. En het smeltwater van Groenland zal tot een iets hogere zeespiegel leiden. Aan de andere kant kunnen schepen gebruik maken van de noordpassages. Delfstoffen die nu nog onontginbaar zijn wegens de ijzige omstandigheden, kunnen dan worden geëxploiteerd. Ieder nadeel heeft zijn voordeel. Het ware realistischer een tabel met na- en voordelen te maken tengevolge van de opwarming van het klimaat. Dan nog kan opwarming negatief uitpakken, maar is meer overweging mogelijk.

Ik zal niet alle voorbeelden van Stern ingaan. Het voorbeeld van een verdroging van de Amazone vind ik echter heel onduidelijk. Opwarming leidt tot meer waterdamp en dus tot meer neerslag. Het merendeel van de neerslag zal altijd in de tropen vallen, hoe warm het klimaat ook wordt. Welk mechanisme zou dan maken dat de Amazone verdroogt?