El cambio climático ya está aquí

Eso es lo que dice el último informe publicado del IPCC. No es que diga cosas nuevas, pero sí subraya la urgencia del problema, y hace más evidente la necesidad de pensar ya claramente en adaptación, y no sólo en mitigación (sin que eso distraiga de la segunda, que sigue haciendo falta). Anil Markandya, uno de sus autores, lo resume en el blog de Economics.  Me han parecido especialmente reseñables los siguientes aspectos:

- que el impacto (negativo) en la producción de alimentos parece ya evidente

Based on many studies covering a wide range of regions and crops, negative impacts of climate change on crop yields have been more common than positive impacts (high confidence).

- se confirma que esto es cada vez más un problema de justicia social:

People who are socially, economically, culturally, politically, institutionally, or otherwise marginalized are especially vulnerable to climate change and also to some adaptation and mitigation responses (medium evidence, high agreement). 

Climate-change impacts are expected to exacerbate poverty in most developing countries and create new poverty pockets in countries with increasing inequality, in both developed and developing countries.

- por supuesto, el cambio climático es sólo un elemento más de los cambios en nuestras sociedades

For most economic sectors, the impacts of drivers such as changes in population, age structure, income, technology, relative prices, lifestyle, regulation, and governance are projected to be large relative to the impacts of climate change (medium evidence, high agreement).

Richard Tol abunda en esta idea, aunque Marty Weitzman y Gernot Wagner no están de acuerdo con él.

- Y el sector energético también se va a ver afectado

Climate change is projected to reduce energy demand for heating and increase energy demand for cooling in the residential and commercial sectors (robust evidence, high agreement). Climate change is projected to affect energy sources and technologies differently, depending on resources (e.g., water flow, wind, insolation), technological processes (e.g., cooling), or locations (e.g., coastal regions, floodplains) involved.

Otra cuestión interesante es que, a pesar de que la adaptación sea necesaria, no es tan fácil de conseguir: la incertidumbre asociada a la misma hace que sea muy costoso diseñar adaptaciones eficaces, como dice John Reilly.

“Adaptation is place and context specific, with no single approach for reducing risks appropriate across all settings (high confidence). Effective risk reduction and adaptation strategies consider the dynamics of vulnerability and exposure and their linkages with socioeconomic processes, sustainable development, and climate change.” 

Hence, while it’s possible to learn from others’ adaptation experiences, in the end, the specifics of climate change in my place, given my circumstances, and the socio-economic environment in which I live will present me with very different climate outcomes and opportunities to adapt than you will have where you live. 

This fact alone raises the cost of adaptation, because to some degree each recipe needs to be invented anew. What worked in the past likely won’t work in the future—or at least, not as well. And we need to process a lot of highly uncertain climate projections in developing the new recipe.

Aquí tenéis un FAQ descubierto por Revkin.