Wow - not sure if this is really aiki related. However, it is interesting. I definately am more of a non-interventionist i.e. the more you play with politics and law the more people will manipulate the regulations. However I do believe in social support.
Firstly, environmentally, I would make sure people pay for the real cost of environmentally damaging behaviour, and the money actually goes towards remidiation of this behaviour i.e. when islands become flooded due to global warming, costs should be paid for by the environmental taxes placed on fossil fuel use. (At the moment costs for environmentally damaging activities are pretty much externalised).
Also, I would get rid of this fallacy of a 'free market'. There should be a new free market established which enables complete free trade based on internationally fixed agreements on i. sustainable development (i.e. not exploiting endangered species and environmentally damaging costs have to be internalised (above)), ii. non-exploitation (i.e. minimal health and welfare standards at work, though not necessarily minimal pay).
I tink a large global problem is that many governments exploit their population, and therefore much of the population try to emigrate. I would have an 'adopt a country' set up where wealthy countries are expected to help with the welfare and development of a less developed nation. This would also mean having an influence on the countries politics. At the moment many people emigrate from countries with terrible regimes or economic policies to richer countries (often causing racial tension), yet the problem isn't solved; civil revolution is increasingly difficult because of the ability of governments to control the population with high tech weapons. In the 'adopt a country' scheme, gradual opening of emigration can be established (which would further encourage rich nations to assist in the development of their poorer adoptee). A problem now is that developing nations cannot often effect the poltics in despotic regimes (without trying to find some justification for war vis. Afghanistan) since it is seen as neoimperialism.