```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE)
load("HadCRUT4-gl-download20170601.RData")

temp$min = apply(temp[month.abb], 1, min, na.rm = TRUE)
temp$max = apply(temp[month.abb], 1, max, na.rm = TRUE)

```


```{r}
plot(Annual ~ Year, data = temp, type = "n",
     xlab = "", ylab = "Temperature anomaly",
     ylim = range(temp[month.abb], na.rm = TRUE), 
     bty = "n", axes = FALSE)
rect(1961, -1, 1990, +1, col = "gray90", border = FALSE)
text(1961, min(temp[month.abb], na.rm = TRUE), "Reference period", adj = c(0, -.5), cex = .7)
axis(1)
axis(2)
polygon(c(temp$Year, rev(temp$Year)),
        c(temp$max, rev(temp$min)),
        col = "lightblue", border = FALSE)
lines(temp$Year, temp$Annual, col = "steelblue")
```

