Firstly, vulnerable populations such as pastoralists or small-scale farming families depend most on natural resources for their livelihoods. Global warming tends to produce more variability in weather conditions, as illustrated in the above-mentioned case of the Maasai woman in Tanzania. The rains were delayed for weeks, if they came at all, and rainfall was well below average for the fourth consecutive year. Local knowledge to respond to extreme weather conditions, built and passed on for centuries between generations, is being devalued. Animals perish, harvests fail, incomes dwindle, and nutrition is scant. As resources become scarcer by the day, the pressures and claims on their use increase, and conflicts surge.