I think the most important effects from a human perspective will be those affecting the global food supply.
--Many basic food crops, such as rice and wheat, have shown to suffer reduced productivity at higher temperatures, and some are believed to be close to limits now in some places.
--The subtropical arid zones are confidently expected to expand with increased warming due to expansion of the "Hadley cells." This will hurt agriculture in these newly dry areas, which include some very important productive zones today.
--In a seeming paradox, flooding will also be an increased problem due to increased water content in the atmosphere. (This increase in absolute humidity is now an observed 20-year trend.) This, too, is an agricultural stressor, as we have repeatedly seen (by coincidence or not) over the past couple of years.
--Ecological disruptions due to warming may also be expected, but are hard to predict in useful detail due to the extreme complexity of the possible interactions. But the timing of many biological life events and the geographic distribution of many plants and animals has been shifting very significantly. Crop health and productivity can be affected via pollination, pest, or disease issues.
--Agricultural troubles are likely both to cause, and to be exacerbated by, human conflicts. (People "raid before they starve," and conflict can seriously interfere with farming, as we have seen again and again in history.)