Over 1, 200 high level participants across the world including UN Secretary General Ban Kimoon are meeting in Nairobi to discuss environmental affairs including pollution, and climate change among others at a time when human activities, are taking a toll on environment and ultimately affecting yields.

The U.N. recently upgraded UNEP's standing and the weeklong assembly is the highest-level U.N. body ever convened on the environment.  “We must seize this historic opportunity here in Nairobi – so close to the Rift Valley, the cradle of mankind – to unite the world in its effort to achieve a course correction and shape a new, more sustainable future for humanity, one in which we live in harmony with the natural world and create a life of dignity for all,” said UNEP Executive Director Achim Steiner.

For the UN system, the Environment Assembly – which currently plans to meet every two years – embodies the notion that challenges are best addressed and opportunities realized when the community of nations and citizens of the world join forces to promote economic prosperity, social equity, and environmental sustainability in a holistic manner, Mr. Steiner added in his message on the opening.

Today’s discussion focused on worsening air quality in African cities, as a result of increasing population, urbanization and motorization, and on sustainable development. Participants throughout the week will discuss a new post-2015 development agenda to succeed the UN Millennium Development Goals (MDGs). The Goals, agreed by world leaders at a UN summit in 2000, aim to slash extreme hunger and poverty, cut maternal and infant mortality, combat disease and provide access to universal education and health care, all by the end of 2015 even as it emerges that most of the countries wont meet the set deadlines.

At the assembly, UNEP will launch a new report on South-South Trade and the Green Economy, which the UN agency said will explore the growing movement of development “for the South, by the South.” In addition, a strategic paper on sustainable consumption and production indicators will also be presented this week.

The changing environment — including climate change, pollution, land degradation and access to water— shows that the world's economy needs to be reinvented or progress will suffer, Steiner said.

The conference comes at a time when numerous studies show over 85 per cent of Kenyan farmers were last year inconvenienced by change of weather patterns in their planting or harvesting.Farmers are already seeing changes in the timing of rains, in the
severity of rains through destructive floods, in temperature rises and in the progressive drying of their soils. Climate change experts now say adapting to climate change in this critical sector is not an option but a necessity.

According to climate change experts, the global temperature rise must be limited urgently to avoid serious impacts on African agricultural production, given that 80 per cent of the population in the continent rely on rain-fed agriculture for a living. They observe that at the current rate of temperature increase, global average temperatures will have increased 1.5°C by 2050. The latest science estimates the average production losses by 2050 for African maize at 22 per cent, sorghum 17 per cent, millet 17 per cent,groundnut 18 per cent and cassava 8 per cent.