Edgar Hertwich
Edgar Hertwich
Topic: Research/modelling/accounting on greenhouse gas emissions and resource-use related to consumption and international trade; and life-cycle assessment of energy technologies
Edgar Hertwich researches how activities in society produce environmental pressures, and investigates alternative courses of action to reduce those pressures. He is Professor and Director of the In...
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Number of questions: [3]
Posted on 28/06/2015 12:44:29
Dear Edgar,

Good day!! i am working as a HR in a world renown organisation. I would like to clarify from you if Babool trees , in Tamil seemai karuvelam trees are harmful to ecosystem or not? i heard they cause ground water depletion and even make it poisonous. Must they have to be uprooted ?? Your advice is highly needed for us as we have a group which is at the verge to take our Motto to uproot these trees in Tamil nadu, India. Pls clarify us.
Lekhashri Baskar (from India)
Dear Lakharshri,

I am sorry I have no expertise in this matter.


Posted on 27/06/2015 17:59:28
Dear Edgar,

Within the context of the UNEP, do you see the UNFCCC COP 21 as the last chance to reach a global agreement? It seems that if Paris fails, we will enter for sure in the very core of the age of consequences. In this sense, do you think that the encyclical letter LAUDATO SI can be a reference for the COP 21?
Thank you so much in advance.
Antonio Dominguez-Ramos (from Spain)
Dear Antonio,

nice to hear from you! I am not an expert on climate policy. We are very late in the game of climate protection; things would have been much easier had we really started reducing emissions in the 1990s. The longer we hesitate to reduce CO2 emissions, the more the climate will change. Change is already happening and there is a lot more in store, that we have committed to already given all the already existing oil wells and power plants. So I see this as a gradual issue.

There is something positive that has happened in the past decade is that renewable energy has become a lot cheaper and wide-spread. Electric cars are now on the road, no longer a pipe dream. Passive houses are built by the 1000s. We need to get to millions, but nobody can any longer doubt the feasibility of radical emission reductions.

I think we should all have large respect for Pope Francis and his encyclical letter.


PS: For more on this issue, see my blog entry:

Posted on 27/06/2015 06:01:52
Dear Professor Edgar,
Some scientists advocate the construction of global engineering projects in order to offset the effects of anthropogenic greenhouse gases. These scientists argue, for instance, that particles of sulphur could be injected into the upper atmosphere or mirrors could be placed in orbit in order to reflect sunlight. They also argue that Oceans could be seeded with iron in order to enhance growth of phytoplankton that would sequester more carbon dioxide! What is your opinion on such initiatives?

Francis Bagambilana (from Tanzania (United Republic of))
Dear Francis,
good question. These geoengineering options have been an issue of controversy. Some reject them outright, sometimes based on ethical concerns.
I am in favor of investigating these options as a last resort, so that we know how they would work, what if would costs, and what the consequences might be. However, it would be foolish to rely on them and continue emitting greenhouse gases. What we have learned again and again is that if we engage in large-scale engineering projects is that there are unforeseen consequences. In addition, some of the techniques you mention require continuous effort to be effective, such as spraying sulfuric acid into the high atmosphere. If the effort is somehow disrupted, we would have very sudden climate change indeed.